So I tried the Classe DR-6 in my system replacing the Luxman C-05 pre. The Luxman was way better in my opinion. The Classe was much to forward. The Luxman was much more real.
However, I sold the Classe and picked up a Sonic Frontiers SFL-2 line stage, fully modded by Parts Connexion and I also got an SFP-1 Signature phono stage from the same seller. This combo is only slightly better than the Luxman C-05 pre. The Luxman really gives up very little to the SF seperates, it's truly that good of a preamp. However, I've decided to stick with the SF gear and do some tube rolling to see if any further improvements can be made. I'm really happy with the SF gear. It's very well made an flexible. I'm using the balanced outs to the XPA-2's which leaves the RCA outs to do easy comparisons with other preamps. I also tried a Canary Audio CA-801L against the SFP-2 and the SF gear still won out. Very happy right now.
I use a Carver C-5 preamp. I just got my XPA-2 a few days ago to replace my 43 year old Phase Linear 400. So far I'm very pleased with my new amp. Luckily I bought it during Emotiva's holiday sale which just ended 45 minutes ago!
I am using USP-1 with Harrison attenuators on the XAPA-2 unbalaced input, but for my long classical music listening sessions I use Control Freak between the balanced output of Sony DAC HAPZ1-ES and XPA-2 balanced inputs.It seems like I can hear more without a preamp. I switch to RCA input using two switches on the back of XPA-2. In one of the threads I read that it might be a problem: apparently the balanced/unbalanced switches on XPA-2 Gen 1 were not designed for a frequent use.