Help needed with Proac 1SC setup


I need help with setting up my Proac 1SCs. I was expected to be blown away with the sound, but I haven't. The 3-D imaging isn't there, and the speakers sound rather harsh. The bass also sounds too boomy. I reckon I've done something wrong.

My room is rectangular, with a sofa facing a wall 10ft away. The speakers are about 2ft from the wall.

Rest of the system is Benchmark DAC1 feeding an oldish Arcam Alpha 5 (due to be replaced) into the Proac 1SCs. My speakers used to be Castle Trents, which although old and cheap were kicking the Proac 1SC's ass. Maybe the Arcam isn't good enough, but the Proacs should at least sound better than the Castles. What's going wrong?
kbcam
Great post by Gunbei. I would only add you should be sure to give them plenty of "run-in" (or break-in) time. I have two pairs in different rooms, and they started out sounding somewhat harsh, the way you described. They settled in nicely between 100 and 200 hours of play. (I used a Purist Audio Design break-in disc at low to medium volume in a little-used room in the house. Alternatively, you could play the disc in mono with the speakers facing each other a few inches apart.)
I have heard Proac 1SC on several occasions (only with tubes) and they sounded great... in no way do I remember them as lacking dimensionality, boomy, or harsh.. also proacs do take a long time for the tweeter to burn in, I'm told.
Thanks for all the responses, and especially for the great post by Gunbei. The thin and dizzy mids that you intitially had is exactly what I'm experiencing.

I'm actually planning on replacing the Arcam 5 amp with a Levinson 29, when I can get hold of one. I'm also planning to borrow some high-ish end power amps from a friend to see if they fix the problem on a temporary basis. I'm reluctant to give up the Benchmark DAC though, I really like it.

The Castles had a front-firing bass port, so I'm shocked at how much boom I experience from the rear-firing Proacs. Just to check is the advice: 3 or 4 feet between the speaker and the wall is measured from the back or the front of the speaker?
If you like SS amp, Jeff Rowland 5 might be good choice too. I like how it sound the the vintage Mac MC240. Seductive sweet.
Just to say that my problems have been solved by a change in amp. It seems that the Arcam was just not powerful enough to drive the Proacs properly. The Arcam was responsible for the boomy bass and tizzy mids and highs. I've recently tried the Proacs with a Cyrus X Power amp, and they sound amazing. Exactly the nice detailed sound that has been described elsewhere.