A proper contemporary DAP like my €899 Questyle QP1R has zero issue driving a 100dB+ in-ear monitor. Even low-gain mode sits below volume half mast. For portable purposes, there's zero appeal to then add an amp. It'd merely add bulk, weight and unnecessary expense. With the CDM, the sonic upside would be a mild tonal fattening and dynamic boost without any noise penalty. Personally however I see no reason to promote such a pairing. The entire appeal of portafi is a single device. Heck, the Questyle even drives the 92dB MrSpeaker Ether C to perfection. To really test the CDM's mettle, I'd use it with full-sized 'phones of bigger appetites - the kind where not your fiscal can-do but sonic duress goes after an outboard amp. The next photo illustrates my perspective: Ken's Campfire Audio Lyra jacked into the QP1R, with the CDM adjacent all fired up but with no place to go. What a waste? Exactly. But you certainly could hook up the two. I simply prefer sanity to excess.

Here we take the obligatory look inside. All it takes is a 1.5mm hex key. Single triodes have green PCB and are channel specific, dual triodes have black PCB and go either way. A replacement of the triple battery pack only requires pulling the two-prong plug.

The enclosure is a clever puzzle of bottom plate to which the battery sleeve is tacked; the U-shaped perforated rim and its C-shaped end piece; and the cover which slips into a recess to align its bolt receivers with the through holes. When screwed back together, it's a seemingly bomb-proof brick of a marvel. If you don't fancy the orange LEDs in the valve pins, Ken's video explains how to defeat them. Time to lend an ear. Or better make that two.