I'm certainly not one to judge a device strictly on measurements, but a few of the posted ones seem disconcerting on the Lehmann Traveler.

Frequency response 20 Hz to 30 kHz (-0.5 dB) (I'd expect a little better tbh for a portable SS device)
Signal to noise ratio > 95 dB RMS unweighted at gain 0 dB  (About 10-20dB worse per standard depending on weighting)
THD < 0.02 % at 3 mW, 330 ohms  (0.02 isn't bad or great, but it's at 3mW; using an unusual spec might suggest something)
Output impedance 3 ohms  (close to the corrected Meridian at 4.9 ohms and won't help the many IEMs below 20ohms)

Here's the Leckerton UHA6mk2 for comparison:

Max Output Power, AD8610 Op-Amp
16 ohms: 25 mW
32 ohms: 55 mW
62 ohms: 90 mW
100 ohms: 90 mW
300 ohms: 40 mW
(Measurement conditions: Analog input at 1 kHz, output <1% THD)

Max Output Power, AD8620 Op-Amp
16 ohms: 80 mW
32 ohms: 140 mW
62 ohms: 120 mW
100 ohms: 90 mW
300 ohms: 40 mW
(Measurement conditions: Analog input at 1 kHz, output <1% THD)

THD+N
16 ohms: 0.0033% at 1 mW, 0.0045% at 10 mW
32 ohms: 0.0018% at 1 mW, 0.0022% at 10 mW
62 ohms: 0.0012% at 1 mW, 0.0014% at 10 mW, 0.022% at 50 mW
100 ohms: 0.0010% at 1 mW, 0.0011% at 10 mW, 0.012% at 50 mW
300 ohms: 0.0008% at 1 mW, 0.0023% at 10 mW
(Measurement conditions: Analog input at 1 kHz, 20 Hz to 20 kHz bandwidth, no weighting)

Frequency Response, Analog Input
<3 Hz to 45 kHz, ±1.0 dB
5 Hz to 28 kHz, ±0.1 dB
Frequency Response, USB Input
<3 Hz to 21 kHz, ±1.0 dB
5 Hz to 21 kHz, ±0.1 dB
(Measurement condition: 44.1 kHz sample rate)
Frequency Response, TOSLINK Input
<3 Hz to 45 kHz, ±1.0 dB
5 Hz to 28 kHz, ±0.1 dB
(Measurement condition: 96 kHz sample rate)
Output Op-Amps

Internal Power Supply
±6 V, ground-centered, switching converter + low-pass filter

Battery life
Analog input: Up to 30 hours
USB Input (charging disabled): Up to 10 hours

Output Impedance
<0.5 ohm

So either I've biased any future listening to perceive the Lehmann as bad or expectations will be lowered making it sound better.   

Has anyone tried the AD8620 for the leckerton?

but would love to know what else is there that may best the Leck. Ability to drive HE-560 not necessary since this one will primarily be used with the Sony Z7.

 

Triad LISA. If there was anything else I knew of or tried I'd be using it right now instead of the Leckerton. Make sure you get the 4627-b equivalent if you do.

Those looking for a portable amp that can drive both sensitive IEMs and hungry headphones might wanna hold off for a bit. Something's coming later this year. Will support both balanced and single ended. Sounds like a high end desktop amp. Price is competitive w/ similar portables. Can't say any more.

My favorite portable amp so far has been the Cypher Labs Duet but it's rather larger and doesn't give much volume knob usage with iems. But it sounds awesomely large and dynamic with a great black background.

I didn't care for the Triad Lisa when I was able to borrow one. Used it with the PSU too. I thought it made my HD600 a touch hot in the upper mids.

If staying on the small side like the Leckerton, the Vorzeamp Pure II is worthy. It's super tiny, has an excellent black background and crazy wide left to right separation. The center image seems a little stretched thin with the UERM but very nice with the EarWerkz Legend. Probably doesn't beat the UHA-6s in resolution (not much does) but it will beat it in staging and possibly background silence. But it's on the expensive side- $565. Not sure on its performance with headphones though, I'm only IEMs now.

I want to hear the Cypher Labs Picollo sometime. Seems like an interesting design and I really like the previous CL gear I've heard. It's tiny and much better priced than the Vorzuge.