This review is for the A-S301, as Amazon seems to lump all the reviews for all the models together. I wanted to build a small 2ch system for music in my small office. Keeping to a budget under $400 I was cross shopping this with the NAD C 316BEE and the Cambridge Audio Azur 351. The connectivity options won out (the NAD would need a phono preamp, and both a DAC. I realize the Cambridge has one, but its USB only. I needed the Optical and Coax connectors for my equipment). The Yamaha, on paper anyways, also had more power which, while not important for my use, was a bonus. Even though the Yamaha was a much bigger and bulkier amp, I went for it. As I said in the headline, the item works great, but I had to replace my first one. The first one, while working perfectly and sounding great had a defect in which if the unit was turned off, a relay would randomly click inside, sometimes within minutes or even seconds. Annoying for sure. Assuming maybe I had bad power going to it, I tried different outlets and even brought it to a different location, no improvement. That being said once powered up, it worked perfectly. I called Yamaha support and they told me this behavior was not normal, so Amazon to the rescue, I got a new one. The new one works great and no bizarre clicking.Now for the review, I certainly don't consider myself an "audiophile" my expectations are probably "mid-fi" at best and this unit meets my expectations. I have it connected to a pair of SVS Prime Bookshelf speakers. For sources, I have connected a Vizio TV, a PS3 Slim, a Stanton T.92USB Turntable, and a Yamaha YBA-11 Bluetooth Audio Adapter. The PS3 is connected via HDMI to the TV, and the TV optically to the amp's built-in DAC. The Bluetooth Adapter is connected to the DAC as well, via coaxial, and its power is being provided by the included USB connector on the amplifier. The turntable, while offering pretty much every means of connection possible, is being connected to the "Phono" input of the amp via an Audioquest Evergreen RCA cable.So for the build quality, it has a nice thick and solid brushed aluminium face plate but yes, the knobs are plastic. The controls however do have a nice action to them and work very well. Looking inside, the layout is very nice including dual heatsinks and nice oversized components. Wiring seems to be kept to a minimum and every section is isolated to its own separate circuit board. The circuit and component layout seems to be a pretty thoughtful design. for both short signal paths and serviceability. Around back are a nice set of binding post connectors for both an A and B set of speakers, a permanently attached power cord, impedance switch, a switch to enable an energy saving auto power off (after 8 ours of non-use) plenty of RCA inputs(5), a coax and optical digital input for the built-in DAC plus a USB port to supply 5v power. Please note, you cannot connect a USB audio source to this jack, its for power only. Last but certainly not least, a Phono input suitable for MM cartridges. The included remote, well its functional, but has many small non backlit, hard to read buttons and feels very cheap and plasticy. Its also silver, funny being that the A-S301 is only available in black in the U.S. I wish it matched. Like I said, functional, but kind of disappointing compared to the amp itself.I've had no problems with the DAC and any of its digital inputs. They sync up and remain connected, and the sound, while some may say is not as good as a standalone unit, sounds very good to my ears, smooth and warm sounding. Personally I think it sounds better than the same inputs on my Marantz NR-1604, a 7.1 receiver that I also own, but my speakers could be coming into play here. The RCA connections are fine, no hum, hiss, or anything bad. As for the phono stage, I've read some reviews that say its not all that great. Well to me with my turntable, (Stanton T.92USB) vinyl has never sounded better. I should mention I upgraded the terrible included cartridge to an Ortofon S-120. Before connecting to this amp, the turntable was connected to my Marantz and I have tried all the inputs. USB to a PC was by far the worst, followed by RCA line level, Coax digital actually sounded a bit better than RCA, go figure. Now using the proper phono input offered by this Yamaha the sound is by far the best. Bass is much more solid, mids are smooth, and highs, which for some reason were always lacking are once again present. I've had the T.92 turntable for years and to be honest have never really liked the sound. This Yamaha is finally making it sound like it should have in the first place. I can only imagine what an upgraded more for listening and not DJ use turntable may bring. So for me, the built-in phono preamp is very much a win.Finally onto the overall sound. The amp is still "burning-in" as they say, and while I generally don't buy into that, I did notice a difference when I got my replacement. I had used the first one for almost 2 weeks and had come to really enjoy the sound, very neutral, smooth, but articulate and powerful for its class. When I received the replacement, how can I say it, the sound was almost "boxed-in" by comparison. That being said, I now have probably 15 hours on the new one and its already opening up and sounding better and better as time goes on, so be sure to give it some hours of use before passing judgement on the sound. My other amp choices might have been better, but i'll never know. I do feel with music especially, the sound does compare very favorably to my Marantz NR-1604, a more expensive 7.1 unit. The Yamaha just sounds a bit warmer and inviting, especially when pushed. The 60w/ch power rating is probably a bit on the conservative side. The amp has no problems driving my SVS Prime Bookshelf speakers (8ohm, 87db sensitivity, 20-150w recommended power, 6.5" woofer, 1" tweeter) to extremely loud levels if asked.So to sum it up, the A-S301 offers nice sound, plenty of power, excellent connectivity, and great build quality. The built-in phono stage and DAC are NOT mediocre but actually sound pretty nice to me, and for most may never need to be upgraded. This is a great entry into better than average 2 ch audio. As long as I don't have any issues with the replacement, I hope to be happy for quite some time.UPDATE 4/10/16 Since this review I have upgraded some of my equipment (my turntable to a Pro-Ject Debut Carbon DC, and just today a U-Turn Audio Pluto phono preamp.) I have been using the Pro-Ject turntable for months and it has been great, a solid upgrade from my old Stanton. This Yamaha continues to work without issue. I wanted to talk about the built-in phono preamp. While many have complained that the preamp was sub par, I disagreed, however had no real basis for comparison. Now I do. I still stand by that the built-in works well, but its not the "end all be all" As I mentioned earlier, I just purchased a U-Turn Audio Pluto preamp due to some very favorable reviews online. After some serious A-B testing, its probably not surprising that the Pluto sounds better, the difference however is not as huge as one might think. Output level is similar enough not to matter. Background noise/hum is a little cleaner on the Pluto. Bass output is comparable as are the highs. Where the Pluto excels is at midbass, much more pronounced than the Yamaha built-in but certainly not too thick or muddy. The resulting sound is warmer and fuller, and in a good way. Certain LPs had an almost brittle or thin sound quality and could be fatiguing at higher volumes when played through the built-in. I'll be keeping the Pluto. All that said, given the price point of this amp, the built in is sufficient and still does a decent job for what it is, although if the purchase of the Yamaha is based solely on inclusion of the preamp (it was for me) just know that going with a dedicated preamp may yeild more pleasant results.