It sounds minor, but I really don't like the rear power switch. On my main system I have a 1983 Harmon Kardon PM-650 integrated amp. I use a remote power switch so I guess you could get around it.
Great comparison test and review! 1) Variable line level output for adding a sub is important. Most users upgrade path is to add a subwoofer. I agree with your conclusion. Buy the one that has the features you will use. But the hidden answer to the riddle of which one to buy is actually the Wiim Pro that was briefly shown in the video. The Wiim will take care of the features you may want or need, such as EQ, Bluetooth, Preamp/Source selection, etc.
+1 for Wiim. They even provide FM radio stations without the crappy reception of typical wired antenna stereo receivers. I know most people don't care about local radio but I was pleasantly surprised when I saw that and tuned in through the app. I've never heard fm radio sound so good.
Tip: The secret with the A300 is to use it in balanced mode (XLR cables), and to upgrade the Op Amps with Sparkos Labs versions. I can't recall how many Op Amps it takes (because I changed them out 1.5 years ago) but I believe with mine, I had to replace 4 or 5 of the opamps with the Sparkos Labs versions (and that can get a bit pricey). But boy did the combination make a huge difference. With balanced inputs and the upgraded Op Amps, the sound becomes more dynamic, and more closely features the warmth of class AB models. In addition, the balanced mode makes the amp quieter - meaning, no hums or buzzes. Mine got elevated so much that it has become one of my go-to amps - it has become that good. Music becomes more open with a dynamic and wide sound-stage. Prior to the upgrades, and using just the RCA input with the stock NE5532 IC Op Amps, the A300 wasn't that impressive (let's say over the A07). Just saying...
I haven't tested the A300 ... but the narrow gap between the 8 and 4 ohm power tells me Aiyima has implemented the output current limiting feature of the TPA3255 to prevent power supply shutdowns at higher volumes. You will get comparable sound right up to the level it starts current limiting on 4 ohms, then the dynamics will suffer a little bit. The TDA7498E chip was originally designed for powered speakers in monitor/sound reinforcement roles. There is a bit of background hisssss and they clip very harshly. Not my favourite Class D chip.
The A300 appears to have socketed op-amps. As does the A07 Pro. So, an important upgrade path for these. I *wish* the A300 got larger binding posts. Roughly doubling the power from 8 ohms to 4 ohms is a good thing - it means that in actual use, it will have plenty of power. NO speakers are a simple impedance - all vary by frequency. Having the current available to double the wattage means it is actually can use all the power it has. When the 8 ohm rating is equal to the 4 ohm - the 8 ohm rating is usually not meaningful - in that most speakers are below 8 ohm over part of the frequency range, so they will never hit that limit. The lower impedance portions of the frequency (usually in the bass and midrange) are what matter.
That’s a good way to think about it Neil. In my experience the speaker sensitivity has played a bigger factor in actual output than the amplifier so be it that it is a well designed amplifier. Do you feel that in most cases when the 4 and 8 are similar we are current limited?
@@MattCoykendall1 I feel that when the ratings at 4 ohms is the same or nearly the same as the 8 ohm, then the 8 ohm rating is not as meaningful - i.e. the actual power you will get at ohms will never get to the rated level, because typically speakers have at least some part of the spectrum at less than 8 ohms. This is usually the case lower in the spectrum, and the bass is where most of the power demand is - so the more important rating is the 4 ohm. I should say that speakers with round voice coils (obviously this is most speakers) have more varied impedance. Speakers with flat voice coils - like planar magnetic drivers or the Linaeum tweeter have much more even/constant impedance.
@@NeilBlanchard Hi Neil ... the "nearly the same" power rating is probably a function of current limiting on 4 ohm loads, or loads that dip to 4 ohms (the chip doesn't care which). The TPA3255 has self-protection that can be used to limit output current, preventing power supply shutdown. The gain linearity will be perfectly normal until it hits the current limit, then it starts to compress. The details are in the data sheet, if you want to look them up.
A balanced input takes two identical signals with one inverted. It lets them enact some pretty nifty cable noise rejection and also lets the amplifier connect up with pro-audio gear which almost universally uses balanced signalling.
