First, AVU this isn't really directed at you. You just mentioned "balanced" which started me thinking about something that's been on my mind on Head-fi, so nothing personal. I've not heard any of the gear you reference and this is not directed at your inquiry...
Since this is a DACPort thread, I write the following only to share my engineering/user persepctive on balanced vs. class A because I really think the whole "balanced" thing is over-hyped on Head-Fi and it feels to me like a lot of people assume balanced is somehow "better" than other topologies and class A seems to be perceived as less desirable. There are many fine balanced amps out there, and balanced interconnects serve a very useful purpose in electrically noisy environments like studios or for live music. But balanced is a means to an end, and there are other ways to get equal (or better) sound quality.
IMHO, the great advantage of balanced amps is that out of phase AB amps produce *mostly* out of phase crossover distortion, allowing the two circuits to null most of the inherent distortion in the amp's crossover zone (and that is a big deal to me as an engineer, as crossover distortion is quite objectionable to me). So it has an inherent ability to create cleaner output without (as much) global feedback.
A class A amp has no crossover distortion, as the transistors are always on. It also has half as many components in the circuit, generally has half the output impedance, because it's always at "full power" there's no question of saggy power rails, or phony "peak power" specs, and a few other lesser advantages. A good class A circuit will usually have less distortion than a class AB before feedback is applied.
Then you have the question of parts quality, circuit design, etc. At a given price point, a balanced amp will require twice the parts, which may mean (not always, to be sure) cheaper parts are used, or the price will be higher.
I'm no fanboy of one approach, I think they both have merits. My home theatre is powered by the awesome Theta Dreadnaught amp, which is 2KW+ of incredibly articulate 5 channel fully symmetric, fully discrete balanced power. On the other hand my primary 'phone amps are both class A.
In the end, there's no hard rule-of-thumb, because there's a huge variable in circuit topology and quality. Here are my general considerations when I look at amp topologies:
1) If you need a lot of power, like home theatre, forget class A unless you have your own power grid. Balanced is a great way to go compared to typical class AB or D home theatre gear, but it can be pricier because you have twice the circuitry. It also tends to use 2x the idle power.
2) For lower power applications like headphones (or horn speakers) be sure to check out class A and keep an open mind. It can often give a sweeter and cleaner sound, and many of the circuits have less reliance on feedback.
3) Balanced amps often sound better than class AB, but a good AB will outperform a mediocre balanced.
As always, YMMV, others will have totally different perspectives, and there's no substitute for actually listening to the amps when possible.
