I have an HK 240 at it sounds great with my 340SEs/170SEs. It originally retailed for $800 but I picked up a refurb from the Harmanaudio official reseller on their ebay store for around $250. The 240 is rated at 65w x2 or 55w x7, and S&V mag's measurements have it putting out about the same amount of power as the 100w x6 (6ohms) model Panasonic digital (5x or 7x?) -- I had a thread here on Ascend last year about it.

If you can, definitely add room treatments. Even just an absorption panel on either side of the room at the first reflection points (assuming the walls aren't over 6' away from either side of the speakers) will do wonders for the sound, imaging, soundstage, clarity, etc.. Adding some bass traps to the corners will do wonders for the bass as well - like you wouldn't believe. GIK Acoustics has very reasonable prices, and you can also look into making your own treatments for much less (if you are handy with tools and have the time).