i actually was just thinking today that the headroom desktop balanced package (bal amp w/ stepped attenuator + bal DAC + 650/701) is probably the best deal in audio at the moment in terms of price to performance. if someone had nothing or very little and 2K to spend, i would tell them to get this package. you would not feel the need nor would it be necessary to upgrade for a very long time.
When the first time I have heard fully balanced HD650 from out of Rudistor RPX100 amp I was shocked, because you do not hear the same HD650 at all. The energy, the whole presentation, clarity, detail bla bla bla, but the most of all THE PUNCH, oh yes, very good. I need to hear them again and I will do, but will give them much more listening time, than the last time.