Topping have produced some cheap little amps in the NX1 and NX2. I also have an NX3 which has a little more power although I do hear very slight hiss with low impedance headphones. Just got my hands on an NX5. It's narrower than the NX3 and just slightly longer. The volume know is recessed and cut into the case. High and low power and bass boost. Solid aluminium case on both. Comes with a rubber mat so dals don't scratch it if you put them together, plus two rubber bands, short patch lead and a charging cable. First thing I noticed on switch on was a relay. It clicks in just after switch on and clicks out again when you turn off. The case screws are in the sides, not the back and front. First impression is that it is very quiet and perhaps a little more lucid sounding than the NX3. Not a lot in it but I instantly felt that the bass might be a bit faster. Not sure since the NX3 is no slouch. It has more power and drives my AKG k712 to loud volumes!! The NX3 is going at around £59 and the NX5 at £110. Nearly double so my feeling is that the NX3 is better value although I think the NX5 is just a fraction better in terms of lower noise floor, more power and maybe a slightly more controlled bass. Slight improvements for nearly double money. Problem is that they're now creeping into Fiio amp prices and so there is stiff competition.