Hi, I'm a user of the H/K AVR 255. This is the Asia/Europe equivalent of the AVR 254.
It is a very good mid range AV Receiver in terms of sound quality, power and features.
Other shops and internet forums compared them to the Onkyo TX-SR60x series, the Denon AVR 191x series and well as the Yamaha RX-V66x series.
In terms of power, it is rated at 65W per channel on 2-channel stereo and 50W per channel in all channels driven. Most of the Japanese brand such as Onkyo, Denon, Marantz, Pioneer or Yamaha, etc. rated their AV Receivers in 2-channel stereo only which is somehow misleading.
One of the gripe I can say is the firmware update process of which you need to update the AVR via RS-232 and WinXP. The latest firmware update as of Jan. 2011 is the 07-01-2010 01, AFW v0.98.3.1, DSP Version 1.2.9. Another issue is the EZSet/Eq which is only good for movies. Turning this OFF and manually adjust the speaker level via SPL makes the speakers more 'ALIVE' specially when listening to music or CD.
It does not have the Audyssey EQ or the Dolby Pro Logic IIz. It only has 3 HDMI inputs and 1 HDMI output but it has the preamp outputs. You can use an external multi-channel Power Amplifier if you want bigger sound applications.
My set-up is 7.1 and composed of Bose 701 Series I, Bose 301 Series IV and V, Bose VCS-10 and Velodyne VX-10. As per my experience, the AVR 255 can drive these speakers at reference level without restraining.
I do not own Blu Ray Player or PS3 but have Popcorn Hour A-200 in watching 1080p24Hz movies.
Before I bought the AVR 255, I do research as well and compared it to the Onkyo TX-SR606 and Denon AVR 1910 in demo. In my opinion, the AVR 255 is better than the SR606 and 1910 in terms of sound quality (warm sounding I guess). Just an opinion and do not want to offend others.
Hope this helps.