Do you have both of those Pioneer receivers.
No receiver from Pioneer sounds better than what was built untill 1979, lot´s of options and superb sound , new speakers just make´em top sound quality if we aren´t talking in 25.000€ to 50.000€ each component.
Only today they are very old , they need to be restored to original specifications, or if taken care of through out the years, mine were getting some attention whenever i felt they were not has i was used to hear,
and the power might seem too low but they sure blast the hell of more powerful and modern speakers,
as an example the CDM7 from B&W , expel their grills when connected to a SA-9900(76)a integrated amplifier, with loudness on,
in early 90´s some amplifiers were sold with good sound quality like the A-717mk II or the 89, A-91D(digital inputs and outputs with capability of connecting a digital processor of any kind.
In the 90´s i bought the most expensive AV receiver from Denon, was huge and the remote did the set up , without it it´s doing nothing,
tried lot´s of other remotes and nothing , it was stolen to a dutch friend of mine while driving through Spain
To end ,Infinity speakers always surprised me for the best and amplifiers i do like Accuphase and Luxman,
some years ago ,not many, found a Yamaha integrated amplifier with needles for the power with a good sound quality the model i heard was 70+70watts at 8 ohms,
and receivers also a few years ago i did liked the new Technics series that sounded amazing with some Technics tower speakers,
New or Recent Pioneer AV receivers ,look good seem to have it all but sound wise are worth nothing, my opinion only