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Discussion Starter #1
Home Theater Shack 2015 High-End Amplifier Evaluation Event Reporting and Discussion Thread


This thread is a continuation of the High-End Amplifier Evaluation Event Preparations Thread previously under way.

The event has begun. Coming to you from southern Alabama, the Home Theater Shack Evaluation Team has assembled at Sonnie Parker's Cedar Creek Cinema for the 2015 High-End Amplifier Evaluation Event. We have amps, we have speakers, we have tunes, we have great eats, what more could one ask for?

Be reminded of the first law of audio evaluation event execution. They never go exactly as planned. Not everything gets there, not everything works, but you endeavor to persevere and get things done.

We have deal with speakers not able to reach us in time, with cabling issues, with equipment not interfacing properly, a laptop crash, with hums and buzzes and clicks and pops, with procedural questions - - - yet we forge ahead, adapt, evolve, redirect, and forge ahead some more - - - and the task of evaluating amplifiers is underway.

Speakers: We were unable to get the Chane A5rx-c and the Acoustic Zen Crescendo Mk II speaker pairs. We are running the Spatial Hologram M1 Turbo v2 and the Martin Logan ESL. Both are very revealing speakers, baring a lot of inner detail in our recordings. They will serve us well. The A5rx-c will be reviewed for HTS when available.

At the moment, the Holograms are serving as our primary evaluation tool. I will post setup details and interesting discoveries a little later. They are giving us a monstrous soundstage, the kind that eats small animals for breakfast, with extremely sharp imaging and very good depth acuity. They are extremely clear, getting into the realm of rivaling electrostatic transparency. Their in-room response is very good, with some expected peaks and dips, but still very listenable. The high frequency response is extended and smooth. The bass gives you that "Are you sure the subs are not on?" feeling on deeper tracks.

We decided to start with sighted comparisons and open discussion today, and blind tests tomorrow. The Audyssey XT32 / Dirac Live comparison has not been completed yet.

Have we heard differences? Yes, some explainable and some not. One amp pairing yielded differences that several evaluators are convinced they could pick in a blind AB test.

One thing I have learned for sure: The perfect complement to good southern barbeque is a proper peach cobbler. Add great company and you have a perfect get-together.

The Event
  • Date: Thursday evening, March 12th through Saturday evening, March 14th.
  • Place: Cedar Creek Cinema, Alabama, hosted by Sonnie, Angie, and Gracie Parker.
  • Evaluation Panel: Joe Alexander (ALMFamily), Leonard Caillouet (lcaillo), Dennis Young (Tesseract), Sonnie Parker (Sonnie), Wayne Myers (AudiocRaver).
The Amplifiers
  • Behringer EP2500
  • Denon X5200 AVR
  • Emotiva XPA-2
  • Exposure 2010S
  • Krell Duo 175
  • Mark Levinson 532H
  • Parasound HALO A31
  • Pass Labs X250.5
  • Sunfire TGA-7401
  • Van Alstine Fet Valve 400R
  • Wyred 4 Sound ST-500 MK II
The Speakers
  • Spatial Hologram M1 Turbo v2, courtesy Clayton Shaw, Spatial Audio
  • Martin Logan ESL
Other key equipment special for the event:
  • Van Alstine ABX Switch Box, recently updated version (February 2015)
  • miniDSP nanoAVR DL, courtesy Tony Rouget, miniDSP
  • OPPO BDP-105
As mentioned, our deepest appreciation goes to Sonnie, Angie, and Gracie Parker, our hosts, for welcoming us into their home. Look up Southern Hospitality in your dictionary, and they are (or should be) listed as prime role models thereof.

This first posting will be updated with more info and results, so check back from time to time.

Amplifier Observations
These are the observations from our notes regarding what we heard that were supported by being consistent between sighted and blind testing and across reviewers. While we failed to identify the amps in ABX testing, the raw observations from the blind comparisons did correlate in some cases to the sighted observations and with the observations of other reviewers. Take these reports for what they are, very subjective assessments and impressions which may or may not be accurate.

Denon X5200 AVR

Compared to other amps, several observations were consistent. The Denon had somewhat higher sibilance, was a bit brighter, and while it had plenty of bass it was noted several times to lack definition found in other amps. At high levels, it did seem to strain a bit more than the other amps, which is expected for an AVR compared to some of the much larger amps. Several times it was noted by multiple reviewers that it had very good detail and presence, as well as revealing ambiance in the recordings.

We actually listened to the Denon more than any other amp, as it was in four of the blind comparisons. It was not reliably identified in general, so one could argue that it held its own quite well, compared to even the most expensive amps. The observations from the blind comparisons that had some common elements either between blind and sighted comparisons or between observers are below. The extra presence and slight lack of bass definition seem to be consistent observations of the Denon AVR, but everyone agreed that the differences were not a definitive advantage to any one amp that would lead us to not want to own or listen to another, so I think we can conclude that the Denon held its own and was a worthy amp to consider.

Compared to Behringer
- bass on Denon had more impact than Behr, vocals sounded muted on Behr
- vocals sounded muted on ML compared to Denon
- Denon: crisp highs preferred compared to Behringer which is silky.
- Denon is more present, forward in mids and highs than Behringer.

Compared to Mark Levinson
- Denon seemed to lack low end punch compared to ML.
- Denon is smooth, a certain PUSH in the bass notes, cellos & violins sounded distant, hi-hat stood out, distant vocal echo stood out, compared to ML.
- Denon bass seemed muddy compared to ML which is tighter.
- ML more distant strings than Denon.
- Denon is slightly mushy and fat in bass. String bass more defined on ML.
- ML seems recessed compared to Denon.

Compared to Pass
- vocals sounded muffled on Pass compared to Denon
- crisp bass on Denon compared to Pass
- Denon & Pass both even, accurate, transparent, natural, no difference, like both
- Pass seems soft on vocals but very close.
- Denon has a bit more punch on bottom, maybe not as much very deep bass, more mid bass.

Compared to Van Alstine
- bass on Chant track was crisp for VA while Denon was slightly sloppy
- sibilance not as pronounced on VA as it was on Denon
- VA super clarity & precision, detailed, space around strings, around everything compared to Denon which is not as clear, liked VA better.
- sibilanceon Denon, VA has less “air” but more listenable, both very good
- Very deep bass more defined on VA, overall more bass on Denon.

Wyred 4 Sound ST-500 MK II

In the sighted listening we compared the ST-500 MK II to the Van Alstine Fet Valve 400R. The assessments varied but were generally closer to no difference. The Van Alstine got comments of being fatter on the bottom. The Wyred 4 Sound was noted to have slightly better bass definition but apparently less impact there, and slightly less detail in the extreme highs. Most comments about the midrange were not much, if any difference. An interesting observation here was by Wayne, noting that he did not think he would be able to tell the difference in a blind comparison. Considering the ST-500 MK II is an ICE design and the Fet Valve 400R is a hybrid, we expected this to be one of the comparisons that would yield differences if any. As I am always concerned about expectation bias, this was one that I was particularly concerned with. Van Alstine is a personal favorite for a couple of us so I expected a clear preference for it to be present in the sighted comparison. I felt that the Wyred 4 Sound amp help its own with the much more expensive and likely to be favored VA.

In the blind comparisons, we compared the ST-500 MK II to the Emotiva XPA-2 and the Sunfire TGA-7401 in two separate sessions. Of course, in these sessions we had no idea what we were listening to until after all the listening was done. In the comparison to the Emotiva, some notes revealed not much difference and that these were two of the best sounding amps yet. The ST-500 MK II was noted to have the best midrange yet, along with the Emotiva. It was described as having less sibilance than both the Emotiva and Sunfire. Both the Emotiva and the ST-500 MK II were described as unstrained in terms of dynamics. In comparison to the Emotiva it was noted to have solid highs, lively dynamics, rich string tones, and punch in the bass. The overall preference in comparison to the Emo was either no difference to preferring the W4S.

In comparison to the Sunfire, comments ranged from preference for the W4S to not much difference to preference for the Sunfire. The Sunfire was described as having more presence in the midrange, while the Wyred was noted to be shrill, lifeless, and hollow by comparison.

These comments varied a lot, but the points of convergence were generally around the similarities to three amps that would be expected to be most likely to be different, if we found any differences at all. The objective results is that we failed to identify the amp in ABX comparisons to two other much more expensive amplifiers. I would have to conclude that based on the results, the ST-500 MK II represents one of the best values and certainly should satisfy most listeners.​

Audyssey XT32 vs. Dirac Live Listening Comparison

Last year HTS published a review of a the miniDSP DDRC-22D, a two-channel Dirac Live Digital Room Correction (DRC) product. The review included a comparison to Audyssey XT. A number of readers requested a comparison of Dirac Live with Audyssey XT32. That comparison was recently completed during the Home Theater Shack High-End Amplifier Evaluation Event at Sonnie Parker's Cedar Creek Cinema in rural Alabama. This report provides the results of that comparison.

Go to the Audyssey XT32 vs. Dirac Live Listening Comparison Report and Discussion Thread.

Spatial Hologram M1 Turbo Speakers

I was very pleased with the Spatial Hologram M1 speakers we used for the amplifier evaluation, and felt that they more than fulfilled our needs. They did not become "gotta have them" items for any of the evaluators, although I had thoughts in that direction once or twice. But they were speakers we could easily ignore through the weekend. I mean this as a high complement. Never did an evaluator complain that the M1 speakers were "in the way" or "holding us back," and we were able to focus on the task at hand unhindered. That alone means a lot, and may say more about them than the rest of the review just completed.

Here is what they did for us:
  • Because of their high efficiency, amplifiers were not straining to deliver the volumes we called for. We could be confident that the amps were operating in their linear ranges and that if we heard a difference it was not due to an amp being overdriven.
  • The stretched-out soundstage opened up a lot of useful detail for us to consider in our evaluations. In discussing the soundstage at one point, there was a consensus that it might be stretched a little too far and might be "coming apart at the seams," showing some gaps, although this did not hinder our progress. My final assessment is that this was not the case, all due respect to the fine ears of the other evaluators. I elaborate on this point in the M1 Review.
  • They served well as a full-range all-passive speaker, able to reach deep and deliver 40 Hz frequencies with lots of clean "oomph," all without the need for DSP boosting and without subwoofer support.
I thoroughly enjoyed spending time with them, and wish to again thank Clayton Shaw of Spatial Audio for loaning them to us. A complete review of the M1 speakers has been posted.

Go to the Spatial Hologram M1 Turbo Version 2 Speaker Review.

A Soundstage Enhancement Experience

Sonnie's MartinLogan ESL hybrid electrostatics were set up very nicely when we arrived, so we avoided moving them through the weekend. There were some improvements made to the soundstage and imaging by way of treatments, and some interesting twists and turns along the way which turned out to be very informative.

I have documented the exercise in a separate post.

Go to the Soundstage Enhancement Experience thread.

Plain ole user
11,121 Posts
Thanks, Wayne, for starting the thread so nicely and for all of your work, both technically and writing.

Another amazing weekend with an awesome group!

This set of reviews is sure to generate lots of questions and debate. Like the first speaker event, everyone needs to understand that we are not attempting to provide the answers to the perpetual great debates nor tell anyone what they should own. We are taking a journey down a path that interests us and asking questions that are meaningful to US in the context of how we enjoy music. Each of us has our preferences, beliefs, biases, and likes. We try to be open about what those are and, while we go to great lengths to set those aside and learn something, we don't apologize for who we and what we believe and like. We have no intention of competing with anyone nor offending anyone and have no agenda but to learn and play.

I try to make it clear where I start in terms of assumptions, expectations, beliefs, and experience. I am at heart an experimenter and look for explanations for everything. I also like to set aside all of the technical stuff and my attempt to understand the why and just experience the joy of people creating and performing great music. So you get two very different pictures if I am successful at communicating my experiences in these sessions. First, the more objective attempt to understand the performance of the equipment. Second, you will hear me speak completely subjectively about what I feel when listening. For me both are essential but I know that the former will never satisfy me, while the latter does. Ironically, I believe that the latter also yields some of my best assessments of the equipment. That will make the objectivists crazy, but as I said above, I don't do for anyone's approval.

I come to this weekend believing that we will likely be able to hear differences between amps, but far fewer than most audiophiles would report. I think we will find more differences in open comparisons than we can validate with blind testing. I believe that blind testing makes it very difficult to confirm differences but at the same time the characteristics of amplifiers that are reported by many reviewers are far exaggerated and unrealistic. I come with assumptions that some of the amps are better sounding by a slight margin but I don't expect that I know which ones they are. I came expecting more out of the Pass and Krell than others, but just based on prior listening to other products from those companies and my appreciation for the designers.

We will see what happens...the first day of listening has been interesting, with some differences noted in sighted listening and no differences in some comparisons. We'll see tomorrow how those observations hold up to blind tests.

Premium Member
15,054 Posts
Home Theater Shack 2015 High-End Steak Evaluation Event Reporting and Discussion Thread

There, I fixed it :drool:
:rofl: :rofl: :rofl:

Gotta love that!

868 Posts
Sonnie the prankster showed up tonight with his Oppo remote app on his iPhone, messing with the Oppo track selection while the listener trid to select and listen to tunes. After supper, the seriousness level often takes a bit of a downturn.
Haha you guys are having too much fun. Wish I could be there, even if just a fly on the wall (couldn't eat very much peach cobbler in that case though . . .)

3,697 Posts
The Cedar Creek Cinema is delivering the best sound I've ever heard in a home, Angie and Sonnie are the best hosts one can imagine, my listening companions are the best group of enthusiasts one could assemble for a weekend of A/V fun, Preston's ribeye was the best steak I've ever had, and Sonnie was thrashing my little Exposure into his EM-ESLs for a long time, longer than he spent with any other amp, thus far. Of course, that means he likes it best and the evaluation is now, for all intents and purposes, over and we are just going through the motions. Right? Right!

I am in the subjective camp, feeling that I can perceive small differences between most amplifiers, but also feel that these differences are largely overblown, in general. Today has confirmed that feeling, for me. Save one instance, I have not found any large differences that, blinded, I would be willing to put money against were I a betting man.

1,295 Posts
The Cedar Creek Cinema is delivering the best sound I've ever heard in a home, Angie and Sonnie are the best hosts one can imagine, my listening companions are the best group of enthusiasts one could assemble for a weekend of A/V fun, Preston's ribeye was the best steak I've ever had, and Sonnie was thrashing my little Exposure into his EM-ESLs for a long time, longer than he spent with any other amp, thus far. Of course, that means he likes it best and the evaluation is now, for all intents and purposes, over and we are just going through the motions. Right? Right!

I am in the subjective camp, feeling that I can perceive small differences between most amplifiers, but also feel that these differences are largely overblown, in general. Today has confirmed that feeling, for me. Save one instance, I have not found any large differences that I would be willing to put money against were I a betting man. That is the best way I can describe my take on an endeavor such as this.
Ok... then take the earplugs out and try again :rofl:

4,838 Posts
Discussion Starter #15
We spent Friday getting acquainted with the amps, listening to different amp pairs seeing if we could perceive differences. Most of us believed we could hear some subtle differences in some cases. In two cases, measurements showed there were differences that could be audible.

Last night we had some fun time comparing the ESLs with the Holograms. I am surprised how much alike they sound. Both have that easy, effortless clarity about their delivery that I have grown attached to. We have driven them pretty hard, and neither has shown signs of getting tired or holding back. Both are delivering monstrous soundstage with incredibly sharp imaging.

The Holograms have been our primary detail microscope for amp evaluation. Their wide soundstagre helps separate individual sounds and lets us hear the finer points of detail.

For the most part, the differences we have perceived have been impressions, not extremely specific. Today we will have a chance to try to confirm them.

A couple of us have noted that we heard no differences in the last 2 or 3 pairings yesterday, and wonder if that was a result of fatigue. So we may reverse the order of some pairings so we are hearing those last amps from yesterday with fresher ears today.

Today we will do blind testing for differences we thought we could hear yesterday.

Lots to do, must get busy.

22,577 Posts
I have conceded that my ears are inferior to these other guys. I literally cannot hear any differences between any of these amps thus far, even in some cases knowing there was a 2-3dB difference in a couple of the areas of the frequency response. At times I think I can hear a ever so subtle difference, but then I can't seem to repeat it with any consistency.

Being the above situation... it hardly serves any purpose for me to be a listener in the ABX blind testing round. Therefore I will be the setup guy for the blind testing. I have setup the following two amps as Amp A and Amp B:

Seriously? You really thought I was going to tell you what two amps they are? NOT!!!
Each of the four blind panelists will listen to X. X may be A or B ... and can be different for each panelist. After each panelist listens to X, I then switch the ABX box to Amp A. The panelist then gets to listen to Amp A and Amp B ... and can switch freely between the two amps. Each panelist will attempt to determine two things: 1. Which Amp was X ... and 2. Did they notice any differences between Amp A and Amp B. At the end of all testing... amps will be revealed and notes compared. In some cases I will pair the same two amps as yesterday so they can compare their notes from yesterday (knowing which amp was Amp A and Amp B) to their notes today (not knowing which amp was Amp A or Amp B).

Let the fun begin!

2,454 Posts
I've always felt there was more to be obtained with upgrading the speaker as opposed to the amp. If you have enough power to deliver the headroom, a good speaker will deliver. And treating the room is also paramount. Isn't it nice how good Sonnie's room preforms? Makes these evals better.
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