Amp sounds thin

I recently bought A Classe ca 200 amp.It is brand new looking inside and out, and seems in working order. But to me it sounds muted, dull, and uninvolving. It doesn't even sound as good as the thrift store amp its replacing A Yamaha built in 1974. Ive tried different speakers, interconnects and sources with little luck. I don't have another preamp so I cant rule out my preamp,but I can only say it sounded pretty good with my old amp. the only thing left I can think of is maybe it doesn't play well with existing equipment or I just don't like the sound of this perticular amp. My sources are a linn lp12 and a cary cd player, speakers B&W dm604, preamp PS audio 4.6 and cardas and straghtwire cables and interconnects. please help, I welcome any suggestions.
Difficult to say whether something is wrong with the amp. I owned a Classe CAP-151 a couple years ago and will say I never warmed up to it. Although I wouldn't have characterized it quite as strongly as you do, your description would be close to mine. Don't believe there was anything wrong with it, just not my taste.
Did you buy it new or used? If it's new, give it at least 40-60 hours of burned in time before judging it. Classe amps have been known for warm sounding and a good match with B&W speakers. Nothing sounds good right out of the box, IC cables and upgrade fuses needed burned-in time as well.
Clean all of your connections and treat them with Caig Pro-Gold. You might be surprised at how much crud you will see on the pipe cleaners and rags you use on them. I have had high-dollar systems and one day it happens where I sit down to listen and I feel like I don't have the ability to peer into the soundstage like I had been used to. Cleaning the connections takes care of all that for me.
I see that you use the 4.6. Do you use it in passive mode, or active? If passive, you may be having an interaction with the input impedance curve of the Classe. Although nominally 75K ohms, which would imply a high input impedance, it is possible that the load varies somewhat and the voltage divider effect is causing a roll off of low frequencies. Just a thought.
I have not cleaned the connections,but the amp is not new and the pre amp is in active mode. This amp is very quiet so I may have been mistaking the noise of my old amp for music. After 30 years in construction my hearings not the best. I think Timrhu may be right, this amp is too polite for me. I perfer something more "in your face", something that rocks.
I believe Ive traced the problem to my low output MC cartridge.I will now shop for A step up transformer or a outboard phono preamp. Billy