I owned a 304 for quite a few years, then passed it down to my (much) younger brother after I upgraded to a 320BEE. It was an excellent amp for the money. The only reason why I replaced it was for the remote control.
While its a great integrated, its no McCormack IMO. Not that I'm saying Joelv is crazy or hard of hearing. Everyone's system and room are different. I currently own a Bryston B60, and the differences are night and day. There's nothing the 304 does that the B60 doesn't do significantly better. The B60 costs about 10x the 304, so take that as you will.
I ran the 304 with a pair of PSB Century 500i, then a pair of PSB Image T55. It powered them just fine in a small room. The 304 struggled a bit with the T55s in a medium sized room. The 320BEE did a better job as far as grip and control are concerned. I can't imagine the 304 powering a difficult speaker like the Paradgim Studio 100. Maybe in a very small room, but the Studio 100s need some room to breathe, which would cause different problems. Please don't take that as an insult to your hearing. Again, everyone's room, system, and ears are different.
In my different rooms over the years and with my differing gear over the years, the 304 was a great integrated for the money. So long as it wasn't asked to do things beyond what it was designed to do, it performed spectacularly. Having the 320BEE and 304 at the same time, the 320BEE bettered it in every way. Not a night and day nor a huge improvement, but an improvement none the less. The B60 leaves the 320BEE and 304 for dead. Then again, it should.
The only issue I had with my 304 was solder joints at the inputs. One phono channel input and one CD input's solder joint cracked over time. It was about 10 years old at that point. My father being the master mechanic he is, re-soldered the joints and it worked flawlessly for another 5 or six years. It had the green board.
The 304 sadly died about 6 months ago. It was my first non-mass market component. It got me through college and started my crazy hifi obsession. It went with me to graduate school and moved with me when I landed my first 'real job.' I bought a 320BEE a year later and passed it down to my brother. It got him off his mp3 addiction and he's now headed down the right path. I wish it would have made it to college with him, but the 320BEE will admirably take its place. Our 304 will be missed.
JR