A little puzzled by my newly acquired Yamaha A-S801

If you're happy with the sonics of the amp overall, but it is a little "light" on the bass, you might consider (if you haven't already) paying very close attention to power delivery. You can improve low bass energy and control by upgrading everything from the wall outlet(s) -> power distribution -> power cord . No it won't get you the wham of 100lb monoblocks, but you should hear noticeable improvements.  

A few years ago when I picked up the Epos Elan's the seller was kind enough to include a MAC Sound Pipe, which I felt offered a subtle but noticeable improvement in what I was playing at the time, as far as power cord is concerned. I was using either NAC A5 wire, good but difficult due to its rigidity, or more recently some SIGNAL cable, where I have not noticed any downgrade at all, and possibly an upgrade. I tend to keep things minimalist if possible. Yes, my budget isn't ideal, I realize that. I like some of the ideas posted above I 'll check them out.

As just a thought, If you want to continue using the CD direct mode, which removes the tone controls from the signal path and provides a cleaner signal you might try a Schiit Loke 4 band equilizer between CD player and the 801. It is not expensive and better than the tone controls in the 801. It can be found used.

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