I haven't looked closely, are all three amps of the same topology ? I'm thinking the Denon might be the least powerful ?
I've got to do a closer comparo ......
Which 3 are you considering, you have only listed one, the Denon PMA-A110 so far unless I missed a post for some reason.
Without knowing your output power requirements. My concerns with integrated amps are generally the following:
- More often than not they usually short change you on the DAC section, not that they would sound different but they would limit the digital files you can choose from. I believe "CD quality" is already below the threshold of audibility in terms of "sound quality" but there are much more high quality recordings (most important afaic) in the 24bit/192 kHz, DSD256 and DSD512 groups. I would only choose from the ones that don't have onboard digital front end so that I can get choose my own digital front end, be it desktop DAC, network streamer etc.
- Those in the below $5,000 group are typically not more powerful than the mid range AVRs such as the RX-A3080, AVR-X4700H and SR7015. Gene's rave review on the PMA-A110's 4 and 2 Ohm measured output on his bench appeared to be based on the conservative rated output spec of only 80 W into 8 Ohms and 160 W into 4 Ohms. If you look at the numbers though, you will see that it really isn't more powerful than the X3300W he measured a few years ago. So imo, its mostly hypes about that anniversary integrated amp. I like numbers and do rely heavily on bench measurements, but I also believe for real world use, anything with THD+N less than 0.05%, 20,20,000 Hz, from 0.01 W to 2Xrated output would be good enough for anyone except those listen in an near anechoic class hifi room at very low to reference level.
So if it is about the look, then surely the PMA-A110 looks great, but you may find the Marantz Model 30 just as good or better. The Marantz has better specs in general, more powerful and have pre outs, for about the same money. The most important thing for such integrated amps, in my opinion, is the power output into 4 Ohms because while the specified THD+N is just one factor and are typically low enough, it could be a huge problem if you push it to well into the clipping range. At some point THD would shoot straight up, we all have seen enough curves to know that would be bad if you need the power that the amps just cannot deliver without clipping.
On the Denon side, their integrated amps are much more expensive in the sense that the more you pay the less "watts" you get. By the time you pay almost $8,000, you will get only 50 W into 8 Ohms and 100 W into 4 Ohms, no wonder they don't offer those models outside of Asia, where more rich audiophiles are found nowadays. That means Denon integrated amps are bad news if you need more than 200 W into 4 Ohms.
So I would look on the Marantz side of Sound United, or Yamaha's A-S2200 that may not be that powerful either but has the beautiful analog meters and you do get 100 W/200 W 8/4 Ohms in the below $3,500 range. If you are not limited by your budget than there are 200 W/400 W rated ones out there too obviously.
As always, I would suggest you take the first step of making sure you know what you maximum power requirement is going to be in the downsized room. Only then you can choose from those you like and has more power than you need, to ensure in terms of sound quality you won't be going backward from what you have now.