Originally Posted by macgallant
Just setup the avr-x4500h this morning here's a quick comparison vs the avr-x1400h.
1) first thing i immediately noticed is my Q750 are WAY brighter (not in a harsh way though) but the resolution really comes through. Is this because of the extra power, better dac, combination of everything? who knows but it's a definite improvement.
2) second thing i noticed is the Q750's mid bass boominess is gone , bass is slightly punchier but definitely tighter. This was more of a placement issue but because of my rooms placement limitation i can either choose between a small hint of boominess or 0% bass. It looks like audyssey XT32 is definitely doing a better job at taming those peaks. *note this was with audyssey reference, i'll test it with L/R bypass(my usual setting) tonight.
3) third, Imaging/soundtsage definitely improved, everything seems locked in. The Q750 really opened up with the x4500h.
4)My subwoofer resonance issues are gone \o/. This is what made me the happiest overall, you have no idea how irritating resonance can be until you've experienced it.
I think Audyssey XT32 is mostly the difference you are noticing. The brightness is likely the difference between Audyssey Reference vs L/R Bypass. The difference in bass due to the greatly enhanced capabilities of XT32 in that area.
As for increased power, better DACs, might be easier to evaluate that with Audyssey bypassed.
For example, I went from the Yamaha RX-V375 to the RX-A2070 and the versions of YPAO went from most basic to best available. Yet I was never a fan of either for auto-EQ. So I set it PEQ Through, which disables all auto EQ and relies on my MiniDSP 2x4 HD for sub EQ.
The differences in sound between the two Yamahas, YPAO auto-EQ bypassed (just use it for setting levels and distances automatically) were indeed much punchier and more refined bass, and more detailed mids and highs and a cohesiveness to the surround sound and much lower noise/better ambient and low level sound handling.
So, better amplification, DACs, etc can improve sound quality even without differences in auto EQ, but it does seem like the different versions of Audyssey in your case are definitely a major factor.
In my case, while YPAO is much more capable on the 2070 than the 375, it still sounded much better bypassed than in the flat or natural modes.
I do need sub EQ via the MiniDSP, though. And setting my Q150s to small/80Hz and ports fully plugged for best integration with the sub (also the sw distance tweak). Also, using an Auralex SubDude II worked wonders with my Rythmik L12 12" sealed sub. Helped greatly reduce vibrations transmitted through the floor and cleaned up the sound nicely.