Strange as it may seems, I can’t seem to find a bad pairing with the 627. It responds very well to the usual popular headphones like the HD650, Hifiman HE-400/500/6 series and the LCD-2. As I mentioned earlier, it completely transformed the bright and nasty Sony XBA-4 to an extremely musical machine. I was so surprised in hearing the Hifiman HE-6 out of the 627. The 627 is not an extremely punchy amp so I was somehow associating that lack of punch with weak power. But then I couldn’t be more wrong, not only was the power smooth and effortless, but it was also a very nice pairing with the HE-6, and better than amps like the PB-2 and the MK3-B in balanced mode! If only, the bass punches harder but alas it didn’t.
I did expect the amp to have gain matching issues with sensitive IEMs due to the use of the analog pot but turns out I was wrong. Cesar probably hand picked the pots on the 627 cause my unit is absolutely free of any low volume imbalance with the IEMs I use: FitEar 334ToGo, 111ToGo, and the Ocharaku Flat-4.
I also tried a bunch of other headphones with it, mostly dynamics like the HD25-1, the Sony Z1000, ATH M-50, HD598 all with very pleasing results. I also enjoyed the new Fidelio X1 headphone with the 627 as it helps to smooth out the mids and the treble of the X1. With every headphone, there is bound to be a very ideal pairing that I would give a perfect 10/10 score. While the 627 may not be the perfect 10/10 pairing for every headphone I tried it with, it’s an extremely musical amp that I can enjoy very well with seemingly everything I pair it to.
I love everything about the 627 but the slightly soft bass impact and the more laid back pace is not quite the pairing I enjoy for my music which is mainly Rock and Classical.
The extent to which Cesar pushed the design of the 627 to obtain such a high level of sound quality, both technically and musically brings many shortcomings on the other areas. I’ve talked to Cesar about these issues, for instance the 4 hours battery life which I feel is the amplifier’s biggest fault. He is aware of the issues but at the moment he prefers to max out the sound quality department and sort of live with the other shortcomings. I did tell him that I would gladly accept a bigger enclosure if that would mean a longer 8-10 hours of battery life because four hours simply don’t cut it for mobile use. Something up to double the current thickness of the 627 would be worth it if that means a superb sound quality with a 10 hours playtime (Look at Triad’s L3 amp!).
Another aspect of the amplifier that I brought up to Cesar also includes the case work, which I would rate as rough compared to amplifiers from RSA and ALO. It just didn’t feel like a $500 amp (the 627 retails for $499.00). Another “feature” is that the amp quite often doesn’t respond on the first power on. You have to power it off, and turn it on again before the capacitor would have enough charge to lit up the voltage boosting circuit.
Other than that, while I would love to have a thin-slim design like the Apex Glacier and USB recharging like what a lot of other amps have, those are not super-important features to have and I can live with the current case dimension and the wallwart charger of the 627. Some people consider that at the end of the day, sound quality is what matters and that’s what the Portaphile 627 is all about. This amp, in a nutshell is a strong nominee for the best portable amp in the market today. You just have to listen to how this thing drive the HE-6: so smooth, so effortless.