Great review, but I would like to point out the part about noticing a difference with the Quad headphones with regards to the output impedance. I do not think the amp is causing this, as the Quad are planar magnetic and in theory they should not be affected due to planar headphones having a very flat impedance response across the frequency range. This is well documented online if you do some reading on high output impedance with planar headphones.

Also I'll note that I have tried the Campfire Audio Andromeda out of the 4.4mm port and could not notice a real difference when compared to a sub 2 Ohm output impedance source, only a slight change in sound signature of the two devices. So whilst on paper the output impedance looks bad, in use it isn't as bad as it looks.

Hi Oscar, I tried few IEMs with it as as I reported no issues whatsoever, they sounded as good as ever.
However, Quad Era-1 on the balanced out was a different story and they sounded weaker in dynamics, slower and not as punchy I remember them to be.

Hifiman Arya that are harder to drive, sounded faster with incredible dynamics, all the magic was back. The only explanation I have is that the output impedance of DX7 Pro caused that problem with my ERA-1, If you think something else caused that, please explain your theory.

Did anyone heard the dx7 pro vs Burson (play, playmate, swing)?

@dangab I listened to all Burson designs, DX7 Pro is better, but it is also more expensive than Play/Playmate. It's more detailed sounding, offers more power and has additional features (Balanced outs and BT receiver)

@DarKu, do you think the DX7 Pro would work well with my Audeze 2.2 (pre-fazor) and Sennheiser HD800 (SDR modded) using 4-pin balanced out? The DX7 Pro deployment would alternate between ‘fixed volume DAC’ duty feeding a Naim Supernait 2 integrated amplifier into speakers and ‘DAC/headphone amplifier’ duty via the 4-pin balanced output. I assume the former is ‘Line Out’ selected by the remote, whereas the latter is the ‘PO’ selection?

Also, I am unfamiliar with the 4.4mm balanced output; is this superior to the 4-pin output in some way? Thanks, and sorry for all the questions!

@BlueDL DX7 PRO will work wonderfully with LCD 2.2 and with HD800 SDR modded. 4.4 mm is the same as 4pin-XLR, same power just a more convenient and nicer looking connector.