I’m using a Rotel two channel preamp, tone bypassed with the RB-1090. I’ve used the R3 with Yamaha M70 Hafler XL-280, Nakamichi PA-1, Several models of Rotel and Crestron CNAMPX 7x200 (ATI). All very strong amps, but the low end is deeper, tighter, more defined. Transients in tracks like “Fanfare for the Common Man” have more impact, Far more lively sound. It becomes a full tower squished into a bookshelf. Damn fine speaker.
I’ve heard the same with my KEF 107/2, 104/2, JBL L100t, L80T, L7, L5, 4412, RBH T2/r, SV-61/R. All speakers in the same placement. The high dampening factor is really wonderful with the big JBL 12” woofers. My newly restored 107/2 shake my entire home with the right track. Great control. It could just be the quality/nature of this amp. Pipe organ is just crazy on the 107/2. It’s made me rethink my amp choices. I’m not a high volume type of guy, but I shoot for a higher wattage/all channels driven type of amp these days.