Greetings from the Inland Northwest. Just wanted to out myself as Onkyo Integra Separates original owner. The equipment is over 20 years old. I do only 2-channel stereo, haven't made it into Surround sound as yet. Lately I have been able to improve the setup by modding the preamp to provide for a digital equalizer loop . This was done by taking the audio signal right before the tone control / subsonic filter section and high-pass it at ~ 15Hz. The output from the DA goes directly to the hot end of the volume pot.
This way the AD/DA section is driven by the maximum possible signal and the bit-resolution loss is minimized. Originally I did not use the high-pass filter, but it is needed to eliminate a loud pop when changing input sources. I'll have to experiment with some cap-values as I think it sounded just a very tiny little bit better without the cap in the sign path. But hey..... you are not the original owner of equipment this old unless you are kind of old yourself... that would be me. Consequently I may very well be the only guy on this board that can hear pitch very well but not with my left ear due to hearing loss
That said, life goes on and I still love listening to music.
PS: The Digital equalizer is a DEQ2496, using only the digital section and two EMU 0404 USB units for AD and DA conversion
Regards
Rolf