Tube/SS synergy?

well this info fits in with my sense that the music sounds and feels a bit too "compressed" if that's the right word. Although there is good bass, and pretty good clarity etc. the overall quality sounds a bit...well less dynamic than I've heard these speakers perform in other systems using a Pass Labs x250. I had heard that mixing tubes and solid state was the "cats ass" and wanted to try it, but sounds like this just isn't the best match. I am not clear on the theory behind the limitations, I wonder if someone might elaborate on this "low-impedance amp" mismatch with the tubes?

Well your sense of compression could also be caused from this.
It seems that compression is all the rage in the recording industry nowadays.

Cheers,
John

The input impedence of the amp should be at least 10 times greater than the output impedence of the preamp .

Joeb, is your LS-15 with REL caps or InfiniCaps?

I had LS-15 with REL caps and it severely lacked bottom end punch. I replaced the caps with TRT Dynamicaps and it changed the sound entirely. It had more punch, smoother and overall more natural. The difference was substantial.

I now use ARC LS-25MkI(have to say that LS-15 with Dynamicaps come extremely close to LS-25 in sound) with X250.5 into N803 and it is very good. I use ARC CD3MkII cd player. All balanced cables. By the way, in balanced configuration you will get higher output from your LS-15 into Pass amp and it may improve bass output plus you will lower the overall noise floor. ARC is meant to run balanced. Also, before giving up entirely on the LS-15, if yours is with InfiniCaps(better version) try some NOS tubes if you are using stock tubes. Sovteks or EH tubes do not have very good bass drive.

Good luck.