2230 here. You want "Audiophile" sound with a modest budget? Get one too. :thmbsp:
Your 2275 receiver is a pre-amp, amp, and tuner built into one chassis. The 170DC is a stand alone amp only, a separate. It is meant to be used with a separate pre-amp and tuner. It's a very nice amp, but has comparable power output to what you already have. It is just barely more modern in electronic design, by about 2 years or so. You don't need it, and it would not offer any additional functionality. How much does your friend want for it?