Come to the conclusion that my Cayin C5 Portable Headphone Amp (original amp-only version without DAC) was the win of the century. Got one back around 2014 and they're extremely hard to come by now, especially the og non-DAC version with the far superior amp circuitry.
It's insanely powerful for the form factor, time & price [despite being single-ended only] at >800mw+800mw at 32Ohm and the sound signature is still the best I've heard on anything ~sub-£900, it's lush, expansive, powerful, fast but smooth, somehow paradoxically all of the things at once, wonderfully balanced.
The alps pot gets a bit scratchy after a decade, the plastic cap is finicky, but the design is very interesting and retro. The bass boost is probably the best I've ever heard, there's a hi-gain mode which might be required on about 2-3 pairs of headphones in existence. I really wish they'd make a mark ii with the same components/tuning in a balanced circuitry (the ease of output would be bonkers then), a USB-C charging connector, low/med settings on the bass boot, a bigger battery, QoL improvements and tighter construction.
You can occasionally snap them up from Japan or China for <£200 and I'd highly recommend anyone take the dive if you get a chance.
I've just paired it with a Cayin RU7 in DAC-only mode and some Juzear x Z Defiant IEMs and I'm grinning ear to ear like a child with the joy of the sounds coming from foobar2k. A £380 setup that comfortably trades blows with £1000+ setups.
Though as always I stress the importance of the mastering, regardless of what format it comes on, the best setup amplifying and accentuating a turd is rarely great; which often includes hi-res streaming which regularly features padded crappy masters.
This thing has been a reliable back drop to most of my 20s and first half of my 30s, probably my most revered audio device and I wouldn't give it up for the world. Listening to an original UK pressing of Sugar's Copper Blue & an original US pressing of Huey Lewis & The News' Fore! on it right now.. -I Know What I Like-
