Well......
After much research, I decided to get a Pass Labs x-260.8 from Reno HiFi. Kent at Pass Labs and Mark at Reno were very helpful. My reasoning:
Bipolar vs. MOSFET...... I've heard the description of the two as Top-Down vs. Bottom-Up. Not sure if that is really as valid today as in the past but one thing I do know is that I desire a slightly warmer than neutral sound as I cannot stand much sibilance especially in female voices. Past A/B amplifiers I have had seem to have some degree of this characteristic. Legacy Audio used to voice their speakers with Coda (and may still) so that synergy was appealing to an extent. I feel the passive speakers they produced with the big woofers and multiple drivers could avail themselves of the high current available from the Codas. The partially active speakers that Legacy is now producing certainly shouldn't require the amount of current as in the past. The bottom end of the Aeris is drive by 1000 W of class D with a crossover at 80 Hz. The cross over is provide electronically by the Wavelet DSP/preamp so no passive crossover needed. This also means only frequencies above 80 Hz are provided to the upper end (with passive crossovers) for the 10-inch woofer, 8-inch mid, and the two ribbons. I would assume this would reduce the back EMF and current needed. From reading about the different amplifier designs, I seem to come down on the MOSFET side.
Class A..... I chose to try the X-260.8 for a few reasons. Cost vs return is always a factor as I wanted to try the amps while minimizing potential expenses if they weren't for me as compared to the more expensive XA line. The 260's have more available Class A power and I figured it would give me a pretty good taste of the flavor to decide whether to move over to XA-160.8.
I am also hoping the higher slew rate will be a benefit in the speed and detail.
With my speakers I would expect to consistently run in class A. I couldn't find a review on these amps ( only one on the .5 series) but most of the comments about them on discussion boards were very positive. I kind of took other reviews and extrapolated them over to the 260's. Could not find much in used sale histories but don't know if that was because of happy owners or just few being sold. I get the feeling these might be some under-known or under- appreciated amps. Besides, I just like mono-blocks, be it actual or psycho-acoustical perceptions, I don't know.
I've had the amps for a few days now and I must say I was quite surprised how great they sounded out of the box with minimal warm-up time. I didn't want to lose the smooth midrange from the PrimaLuna and on the first song I played, it was evident that the Pass improved the mids immensely. The soundstage is larger and more realistic. The upper end is more detailed and clear with no hint of sibilence. It was like a veil was lifted and the speakers were allowed to open up and show what they could do. I stayed up half the night listening to them with no fatigue whatsoever. I am quite happy with my choice and will take the 4 months that Reno HiFi allows for trade- up to decide on the 160's.
Happy listening!
