I received this amp today and I must say its' a great little amp!
So to start with the downsides, the unit can get quite hot, the power plug is UK, but hopefully is uses a standard cord which you can purchased in any store for almost nothing. I used my old PS3's one.
The unit also does not come with cables, so be sure to have Jack <> RCA or RCA <> RCA cables to get sound from it.
Sound-wise, the soundstage is not the widest, and the metal body can get quite hot while in use.
Oh, and the front LED is super bright in the dark, so you'd better cover it with a black sticker.
Now, for the good points!
First, the sweet sound of tubes. Yes, this is an hybrid tube amp, so the tube is only used for the pre-amp circuit, but the sound is notably smoother than transistor amps, especially neutral ones such as the Soundblaster G6. You still get all the micro-details you'd get on other amps, although they sometimes may be harder to hear. The good point though is that the amp is a lot more forgiving than neutral amps when listening to poorly-recorded tracks or poor-quality MP3 files (yes, I'm looking at you, 64 kbps YouTube).
The lows are great but still lack a bit of kick. They are a bit smooth which some may appreciate - I personally like when I feel like the headphones are vibrating on my head because of the bass, so it's a matter of preference.
The pre-amp tube emits almost zero light hopefully, and the unit itself is pretty good-looking. The metal (or is it aluminum?) body is really nice.
The amp automatically switches between the line output to the headphones output when you plug yours in, and switches back when you unplug them, which is nice, but when you power the amp off and power it on again, the default output will be the line out, even if headphones are plugged in.
Overall, the product is really well-built and the sound quality, at $55, makes it an absolute no-brainer. If you want to discover what tubes sounds like, that's the perfect amp to try!
(FIY, I'm using the G6's as a DAC thanks to its line output, connected through USB to a Windows computer and listening mostly to 16 bits / 44.1 kHZ FLAC files)
I also tried some new tubes with this amp, a 12AU7 from Tung-Sol and one from JJ Electronics. The first one gives a drier sound with heavier bass and I personally didn't like it much.
But the JJ tube really improves the sound : the bass is tightier, punches more, and the mids becomes incredibly detailed. The soundstage is wider and more precise as well. You get a drier sound but still relatively warm. Overall, I'm more than happy with this JJ tube and I think the Ocean really benefits from tube-rolling with this one. So I change my review from 4* to 5* as a simple 20€ tube can really improve the sound.