Full review thread here: http://www.head-fi.org/t/511217/review-ortofon-hd-q7
The short summary:
A bright amp which pairs well with darker headphones and sources. Low gain, ideal for iems and low impedance cans. Crisp and articulate sound, crystal clear highs and clean defined lows, average mids. Tiny size, solid weight, beautiful design that is miles ahead of most desktop amps in its size/price category. Several input options and dual headphone jacks round out the package.
The Hd-Q7 are Ortofon's desktop amp powered by a 16V power pack. It takes in a switchable single ended 3.5mm or L/R RCA unbalanced input at the back and provides 6.3mm or 3.5mm unbalanced output. The volume knob is probably the most prominent feature at the top. Dialling the volume knob is extremely smooth yet firm. There's no chance of accidentally turning the volume up or down. Since it's large, it's easy to be precise.
The overall construction is very solid and presentation is simple and with very clean lines. Definitely an elegant classy looking amp, especially next to a MacBook Pro or MacBook Air.
The Hd-Q7's SQ signature seems to be reminiscent of a higher ended amp with very smooth basses neutral basses, transparent mids and clear/detailed highs without sounding harsh. It's very suited for Jazz, classical, and strong vocals, and probably less so for electronic music or hip-hop. But if you like music with a lot of acoustic instruments, and vocals, the Hd-Q7 delivers very nicely.
My setup is my iMac, Audirvana+, Benchmark DAC1 Pre, unbalanced fed to the Hd-Q7, and the Fostex TH900 as the headphones.
In this configuration, contrary to other reviews here in Head-Fi, I found the soundstage to be quite decent. It's ability and accuracy in separating instruments are amazing. Very well executed timbre.
The amp's delivers quite a bit of detail that it's not forgiving to bad recordings. In that way it's actually quite an analytical amp. However having said that, it's not cold nor uninvolving. The highs, despite being crisp and transparent still sound very smooth, and in some tracks I find that there's almost an added dimension to the trebles.
I've further read in other reviews of the Hd-Q7 to be U-shaped. I personally find it's mids to be quite neutral so at least for me, it's not very U-shaped. Vocals are very smoothly textured along with a very natural bass. In some vocal tracks, the vocalist sounds he/she is singing more from deep within his/her lungs rather than just simply "singing". As a listener I find there's more emotion due to the way the amp delivers it's mids and basses more naturally.
The Hd-Q7 actually sounds much cleaner and clearer than the headphone out of my Benchmark DAC1 Pre, which was rather unexpected. Ortofon definitely managed to deliver an unassumingly high performance amp in a compact package that's decently priced.