Krell has been getting some excellent press on the 175XD unfortunatly the review is in German and google translate isn't working for this article
http://web-extract.constantcontact.com/v1/social_annotation?permalink_uri=2NUNnZk&image_url=http...
The summation in English see above is good
Here is a full review from Tone audio comparing the old non XD amplifiers vs the new XD sound.
http://www.tonepublications.com/whats-new-homepage/krells-new-ibias-duo-175xd/
Dave and Troy
Audio Doctor NJ Krell dealers