Loxjie A40 headphone output

I upgraded from the Loxjie A30 (a gorgeous small desktop DAC/amp that uses an older DAC (ES9023) and puts out a claimed 80Wx2 (4Ω), 40Wx2 (8Ω) into speakers, and only has a ⌀ 6.35 mm headphone jack) to the Loxjie A40. The A40 isn’t quite as nice (it’s more of a standard chassis with a faceplate), and is significantly bigger, but pumps a claimed 85W into my bookshelf speakers and ditches the wall wart for a standard NEMA 5-15P (left) to IEC-320-C13 power cable. And, most importantly, it has a ⌀ 4.4 mm headphone jack for the balanced cables on my cans.

Silly me, I thought it would have a decent headphone output. But.

It is impossible to find specs for the A40’s headphone stage. It’s not on the Loxjie site or in the manual. An Amazon question “[w]hat’s the headphone power output?” got the non-helpful response: “Output Power:stereo 165Wx2(4Ω) / 85Wx2(8Ω).” The reviews that are out there so far don’t address this spec, and a question on one YouTube review has sat unanswered. Sigh.

A teardown shows a CS43131 (spec sheet) powering the headphone section; that component supplies with 30 mW into 32 Ω and 5 mW per channel into 600 Ω. Back of napkin math, that’s probably supplying ~ 7.5 mW to 300 Ω headphones like the Sennheiser HD600 series (HD600, HD650, HD6XX, HD660S2 - though I think the HD660S was 150 Ω?). That’s ... Not much.

An earlier model, the A30, with output measured at about 4 mW at 300 Ω, 30 mW into 33 Ω (although the Specification section of the product page claims “Headphone amp stereo 100mW(32Ω),” a claim repeated in the manual). This reviewer summarized it as: “Very poor. If you need to hear sound you can use it otherwise, you should get a proper high performance headphone amplifier.” A redditor noted, re the A40: “since the previous model had a super weak headphone amp, and the manufacturer doesn't want to publish the relevant specs, I would be very hesitant to take the gamble on it.”

But, I did gamble on it. Sigh. So now I’m looking at the Schiit headphone amps, like the Magnius and the Jolunheim ...