Assuming break in, a couple of thoughts:
1. Get some sound treatment to deal with First reflections to avoid any brightness caused by the windows.
2. Most important, IMHO:
The Revel, Hovland, and Metronome are all VERY revealing pieces of equipment. Anyone of them (less with Metro) would potentially make you feel the system was "univolved" or "thin" at times since there is no coloration and they reveal so much of what is up stream.
To shoot at cabling only is like throwing a rock into Lake Michigan and hoping to change the water level. It needs to be done but not until you deal with the synergy of the R/H/M. Something or two, needs to go. The tube amp is not enough to counter the effects of these 3 peices.
Also, the Revel's alway get such mixed reviews... I wonder. My guess is that they are just a VERY difficult speaker to match. So when you match wrong, you get the bad reviews and when you match right, you get the great reviews.
I would start with changing the speaker. No speaker, IMO, is worth the hassle of trying to find the perfect synergy. I want a system that comes together eaiser than that.
Frankly, I think the Hovland is close to the same as the Revel is in being hard to match. When you get very transparent revealing stuff like this it presents a unique issue in dealing with making the sound "live or warm".
3. The other issue is how long you lived with your last speaker. This makes it hard to accept a new sound as being complete. I won't say more but it is going to, probably, haunt you to some extent no matter what you do.
4. Did you audition this stuff at all? Individually or as a system? These are pretty popular names/models right often people buy the name without thought to the synergy aspect of putting something together. When buying at this level you should have a very clear, and very personal experience, with what the sound characteristics of each piece of equipment you are investing in. If you don't have a dealer where you can hear these things you are at a serious disavantage. Best case of all is to hear the system you want, at home or at store, to fully understand the dynamics.
5. Related to all these things, especially #4, is synergy and picking equipment that works together...regardless of name, price, or style. It is hard to do this but worth the effort. I have been forunate enough to have a good friend who owns a shop who has the magic touch when it comes to this synergy issue. This balancing everything and bringing in cables at the end to touch things up a bit here and there. Don't depend on the cables to transform the system. It will play a part, a very important part, but it is the icing on the cake so to speak.
Hope this helps, have fun.
PS If it was me, I would sell all the stuff and start over.