Simaudio W7 amp sounds not quite expected


I currently have the Simaudio Moon W3 and like the sound a lot.  So I thought getting the W7 would be an upgrade but having bought online it's a bit of taking a chance.
Last night having heard the amp in my system for the first time, the sound is not quite what I expected.  Reading some of the review, I thought it would be a bit forward, neutral.  But what I heard was the complete opposite.  It's somewhat recess and a bit warm.  There is not enough mid range present (like the W3) and the sound is somewhat withdraw and lacking involvement.  The vocal is a bit recess than I would like.  For me the first thing any component needs to do is to effectively communicate the music, but the W7 at least in my system does not do that.  I have to say I am a bit disappointed. 

May be it's my preamp.  I am using single ended.  Anyway, I am getting a Pass Labs XP-10 soon so maybe hopefully it will work with the W7 better than my current preamp which is a Conrad Johnson 17LS.
andy2
I feel stupid because the problem is traced back to a faulty speaker connectors - for whatever reason it slightly short.  Now the sound is a lot more like it.  It's like the W3 but a lot better in every way.
But anyway, will wait for the Pass Labs XP10 to see how it will turn out.
My point was that They apparently take that much time to warm up and settle down after being turned off for sometime.
so even if it's a used unit, and you turn it off then when you turn it back on you'd need to give it two or three days to warm up...
@ andy2,

have read time and again that you need to let Sim equipment run for two to three days to warm up from their cold, then they start adjusting. So if you turn them off for a few days, then they still need two or three days to warm up and settle down...
try that before you do other things...
The power cable suggestion turns out to be interesting.  I currently use some beefy cables I bought from Amazon which has worked out fairly well in my system.  
I just swapped out with the power cable that comes with the amp.  Now the sound is somewhat opposite - the slight midbass hump is now gone but the sound is somewhat lean and leaning toward analytical.
I think I'll wait till the Pass Labs preamp arrives before making any more judgement.
If this is a new amp just taken out of the box last night then a little early to make a judgement on it or make changes.  Also unless you can find a pair of Nordost cables used that you can try and turn over again I would be careful with them as they are not neutral by any definition.  
That's a good suggestion.  I currently have QED  40 reference but only single ended.  Once I get the Pass Labs XP10 and using balance, hopefully it will help.
There is something in the midbass that I wish it could be a bit more speedy.  It's possible that the W7 has a lot more resolution so it reveals the weakness somewhere in the chain - maybe it's the preamp.
Make sure you give the amp plenty of time to warm up and you will need 200-300 hours of running time for break in. Are you using a quality power cable? The W7 runs in class A for the first 10 or so watts IIRC, so musicality and nuance should be pretty much a given based upon hearing this amp in the past.
If you want a little more tipped up sound, why not try a  Nordost cable between the amp and pre?  You may be pleasantly surprised.  
I agree that the W7 is more refined with better resolution and dynamics, but I wish it could be slightly more forward and slightly more nuanced.

W7 should be a more refined amplifier than the W3.

Maybe less upfront , but more resolute with better dynamics.

There could be an impedance missmatch between your pre and the W7. Best thing to do is to borrow another preamp like a Moon 740p to see if the result is better.