Another grateful reader - how nice to read a truly balanced review, that doesn't over-sell a low-budget component but captures what you will and won't get for $120. The tip about gain is very welcome. I'm mucking around with a pair of AKG501s - so much to like in them, but tricky to amp. If pushed they have a tendency to harden so that music with a lot of attack is unlistenable. They do this on the Fiio at high gain, but at low the sound is pretty darn good. You do lose some bass which won't suit a lot of people - the high gain overcomes the low efficiency of 501s and delivers a startling amount of it.
I too am waiting for DHL to deliver a pair of 701s, my second go-around with them. This time I'm going to work up the SS ladder until my ears are happy or my wallet gives out.
Meanwhile BTW they drive the Beyer DT880/600 ohm quite well - a musical combination. Those Beyers are the most accommodating cans I've heard, but IMO they need tubes to give their best.