I have had in my possession the latest creation by Cesar, an OP627/BUF634 Portaphile amp. For those who do not want to read a lot then … I like it a lot.
For those willing to read a bit more ...
1. As in past offerings by Cesar the bass is very well rendered, with plenty of impact without being loose nor is it flabby.
2. A very wide soundstage about 5 rows back thus giving the music a very airy presentation.
3. The decay of the notes is excellent and the hi-hat and snare drums linger thus making for an enjoyable listening experience.
4. A detailed presentation that is easy on the ears, kind of the amp you could just sit and relax on a Sunday morning while reading the newspaper on your back porch.
5. The amp is very musical and engaging, at least to this old phart (53 YO) who listens mostly to jazz.
For the line out dock I used an old "Six Shooter" from ALO, for cans I used:
1. Yuin OK1
2. Westone 2
3. TripleFi 10
4. Creative Aurvana Live
5. Senn HD580
BTW, this amp requires a dual turn on as per Cesar's instructions it has to do with the voltage boost function which Cesar explains on the nincluded instruction sheet. I should point that being a class A design the amp runs a bit warm, would not be noticed if in a jacket pocket or a backpack. IMO it takes about 8 minutes after you turn the amp on before it sounds its best.
The unit has a gain switch so the user can select between a gain of 2 or a gain of 7. I listen at very low volumes so even with the Yuin OK1 i kept the gain on 2. BTW, this amp scales nicely with full size cans and I used a Senn HD580 which sounded very nice. The unit also sports a switch to allow the user to select between red and green as the on/off light color, personally I would do away with this feature and instead allow the user to choose one or the other. The light switch also functions to let the owner know when the battery is reaching a full charge (it blinks).
The amp is by today's standards on the large size but still in line with an iPod and slightly smaller than an iPhone (see pictures below). The unit I have on loan and may still receive some tweaks by Cesar, if so I would hope for:
1. Slightly longer run times, say 10 hours.
2. Slight extension of the top end.
Although the unit I am testing was already used by others I did not know how many hours of burn in it had so I first let it run for 60 hours before my initial critical listening. I then proceeded to burn it in for an additional 60 hours and I felt the unit's clarity, detail, and upper mids improved. I plan on burning it in for an additional 80 hours to see if any additional changes occur or not. Thanks Cesar for the opportunity to try this new amp, more to come.