A little puzzled by my newly acquired Yamaha A-S801

I have had a AS2100 for several years. It obviously has a little more power than the 800. My original system had KEF R3s. I had the same complaint. I think it was the R3s. I added a subwoofer, and everything changed. In fact, I eventually added a second subwoofer. I doubt any amp will give you impressive low end from those speakers. My system has evolved. I kept my AS2100, for my outdoor system, I think it's a quality integrated amp. Yammies don't get a lot of love. Small speakers need subwoofers if your looking for more low end. IMO

Had mixed results with low price Yamaha amps. I found them a bit bright. The Belles Aria amp is excellent sounding but there seems to be something going on with the production, as of a few years ago. I was set to buy one about 2 years ago and was "dissuaded" from it by 2 different long time retailers (29-30 years) who referenced inconsistency in build and product needing to be sent back to NY for repairs. The company stood behind its products and addressed the issues but it took time.  Both eventually stopped selling the line, though I cannot say it was due to this situation. It scared me off as I live far away from any repair facility and gear failure was what had put me into the market initially. On the other hand, the Aria is a gem in sound and you do find some for sale online every so often and Dave Belles past gear has been seen as very reliable. You might check in with John Rutan in Verona, NJ @Audio Connection. He sells lots of Belles, is a big supporter and seems to be a real straight shooter. He shows up on this forum every so often and has a great reputation. I would believe that he of anyone knows what is going on with the brand and would answer honestly as he has a good long standing shop and reputation. I was dissuaded because it is a boutique production situation and have moved to buying bigger brand components with large repair networks. It works for me but my situation is unique so I play it conservatively.

@sifter 

Let the amp burn in more before you ditch it.  Give it 200 hrs or so.  

Well, this weekend I acquired a pre-driven NAD C375BEE, initial listening is very positive. Definitely more immediacy and more satisfying low end. I do, however, plan on doing some comparison listening on a few tracks to see what I think both overall and regarding the upper midrange/top end as well.  NAD heats up a bit more but I have several inches of ventilation space above so hopefully not an issue. 

I've operated a NAD with a couple inches of ventilation for a decade or more with no problems.