@vair68robert Thanks for your post back on 9/11 with the link to the article comparing the Classé CA-2300 and the C-J MF-2550 SE amps running 3.7s. I've been running 3.7s with a Classé CT-2300 (same as CA-2300 except for the case). Starting with the amp and speakers alone, I added a single Thiel SW1 sub via a PXO5 passive X-over, and finally a pair of JL Audio subs via a Thiel SI-1 active X-over. Along the way, I installed an array of tuned (60 Hz) bass traps on my rear wall to fix a severe SBIR problem –– this in addition to more standard room treatments.
The CA-2300 handled the 3.7s quite well from the beginning, but adding the Thiel SI-1 and the dual subs made the most significant improvement. High frequencies were sweeter and stayed sweet to louder volumes, the sound was more transparent, vastly improved extremely immersive sound stage, etc. Adding dual subs with the active X-over lightened the loads on both the amp and the speakers. It's hard to say how much of the improvement came from each component, but I suspect at least some of it had to do with easing the load on the amp. Consistent with the review, while the Classé amp performed quite well on its own, this suggests that there might be room for improvement in its load handling abilities.
It's worth noting that the reviewer didn't prefer the MF-2550 SE in all respects. He preferred the C-J Premier 350SA's weight and soundstage and referenced the Classé's (presumably superior) subtlety. I'm not shopping for a new amp right now, so I'll just make a note for future reference. If your room and budget allow, you might consider adding sub(s) with an active cross-over as an alternative to upgrading to a heftier unit if you're otherwise happy with your amp.
