I've been meaning to write about this for a while now.....
I reviewed the original 627 a while back and compared it to the O2 and the Portaphile V2 Maxxed.
The test set up was all portable/transportable equipment, running from AC, except the headphones which are my T-1s.
- Dell Vostro 3700 laptop, Windows 7, WASAPI (USB audio DAC) (not shown)
From right to left:
- Pico USB DAC -- Regardless of it's diminutive size, I've found this DAC to be every bit the equivalent of more expensive desk top DACs
- Original Portaphile V2 Maxxed -- my ultimate favorite, go to, Portable amp. bar none.
- nwavguy's Objective 2 -- another really good sounding amp, designed by specifications (you guys know the story)
Running through the amps that night I found it hard to hear any big differences.... but I decided to live with them for a while and see how things settled in. I have always found that I develop preferences for certain combinations. My basis for comparison is my go to rig, a North Star DAC, GS-1 and T-1 headphones.
It should be noted that, unlike in the picture, when I volume balanced, all the volume controls were at similar positions.
My initial feeling was that the O2 had more resolution than either Portaphile. That said, it needs 2 9 volt batteries and is the largest of the offerings and with 2 9V batteries the heaviest.
The new Portaphile 627:
I don't care for built in rechargeable lithium battery (even though everyone is using them). Give me a regular 9V that I can get in any supermarket in the US and I'm a happy man.
The original Portaphile is only marginally thicker but it's much smaller and lighter than the 627 and I think the play times are similar, depending which rechargeable 9V you're using.
After the amps have been on for an hour or so the new Portaphile 627 was warm to the touch. The O2 was ice cold and the V2 Maxxed wasn't warm but it's not as ice cold as the O2.
The reason I'm writing this today is that I'm listening to the Pico dac and the Portaphile V2 Maxxed with my T-1s and am simply bowled over by the sound. Since getting the O2, it has been my regular transportable amp and I was under the impression that it had slightly more resolution than the V2 Maxxed. I don't think this is the case any longer. The only change I made to the V2 before listening today was to change the internal dip switch from high gain to low gain, which is still way more than I need for the 600 ohm T1s, and Wow, the V2 Maxxed sounds almost too good.
Of course, the first thing I did was to get out the O2 to to compare them again.
OK, now lets get them volume balanced. Again, it is very hard to tell them apart but after listening, the V2 Maxxed sounds truer to the sound of real instruments, (or more pleasing to my ears), than the O2. And after listening for a while, there is no doubt that I prefer the sound of the V2 Maxxed over the O2. This really doesn't surprise me because I have always been a fan of the V2 Maxxed. It is simply the best sounding portable sized amp I have ever listened to.
Regarding the 627 implementation:
Along the way I have accumulated a couple of M^3 amps. One is the single cased version with an internal power supply and the other is the 2 cased model. I have experimented with all the usual op amps and for what it's worth, I have settled on a 637/627 combination for my 2 cased M^3. Even though Ti Kan showed me, in an e-mail exchange, that the difference between my 637/627s and my 8610s was a -45dB, I still prefer the 637/627s over the 8610s in the real world of listening. As an aside, I find the M^3 with the 637/627 to have the same pleasing sound signature as my Woo 3 with a Cetron power tube and two JAN Philips 6922s.
What I like and what I don't like:
I don't like lithium batteries, I much prefer rechargeable 9Vs because in a pinch, if you go through all your rechargeables, you can get regular 9Vs everywhere.
I don't like the size and weight of the O2. It is only Transportable.
I like the sound of 637/627s in my M^3, so if you like 627s, the new Portaphile is the way to go.
I like the size, weight, and sound of the 8610s in the V2 Maxxed, and the fact that it takes readily obtainable 9Vs is such a plus and it's so easy to have an extra 9V around that the 5 hr play time has never been a problem.
We've had a lot of blackouts up here in the northeast and what do you do when your internal lithium battery dies? With a nice supply of precharged rechargeable 9Vs and a pack of 9Vs from the supermarket, I was able to weather the storm using the FM radio feature in my Sansa Fuze and 2 Sansa Clips. ( the coiled cable acted like an antennae enabling me to pull in stations from NYC, 50 miles away.)
YMMV, mine does all the time, but this is how it sounds today....