My new AvaStar Preamp (with remote) and Double Ultra+ 550 amplifier arrived last Wednesday. I had been using a Wyred4Sound STI-1000 integrated amplifier. So, I'm moving from about a $2500 integrated to separates that cost about twice that much. It's comparing apples to oranges therefore to say that the Van Alstine equipment easily bettered the Wyred4Sound in every respect.
My first impressions were purity and clarity, effortless detail, more controlled and better defined bass, and no grain or etching (as may sometimes account for an impression of more detail). The extra bass detail gives the feeling of deeper bass as well, but I haven't measured it (my Radio Shack SPL meter is not very accurate below about 200 Hz anyway).
The Van Alstine equipment also benefited very clearly from the acoustic panels that I bought recently. I had tried them with the Wyred4Sound but it seemed to dull the sound too much. With the Van Alstine amp and pre-amp it's an entirely different story. The Van Alstines provide a much more clean conduit for all of information on the original recording. Removing the spurious back and side wall reflections provides a big benefit because there's so much more musical information coming from the speakers that getting rid of the room sound doesn't diminish the vitality of the music. With the Wyred4Sound (remember, apples and oranges), the room reflections added a little zip (artificial as it might be) to music.
The reflections also added cloying distortion, however. I made that discovery just this evening. Despite all of the good things the Van Alstine equipment was doing, I was still finding the sound too aggressive and in-your (my)-face. I was fairly grumpy about it, and finally I started brainstorming. I had the wall behind the speakers covered with panels and the walls directly to the side covered. The only possible reflection point was a window along the left wall that has a book shelf in front of it with the tops of books above the level of the bottom sash by about a 5 inches. I always figured it was unlikely to be a significant reflection point. Out of frustration and willingness to try anything, I grabbed a 2'x2' panel and put it in the window. SHAZAM! The problem was solved. Suddenly I wasn't nudging the volume down and puzzling over why so many recording seemed to have this slight resonance in certain mid-range instruments. Soundstage depth improved, and I've been listening for three hours without the slightest fatigue.
One stupid 4 square feet of window. Who would have thought?
I now have the best stereo I've ever owned.
Thanks, Frank!

P.S. I forgot to mention how real and textured cymbals sound now. They sounded fine before, but now they are palpable (you can hear the subtleties of how they are being played). And this is not due to any brightness or treble emphasis. Just clean, musical sound.