|Apparently Cesar is quite proud of his new creation
The first thing I did when I got mine was plugged in my 16 ohms er6i and listened for hiss. There was none. yay! I slowly turn up the volume to look for imbalances between left and right channels... it leans slightly towards the right but insignificant enough to notice (my ears can tell a +/-1db difference in volume between left and right). Note, my sr-71 leans towards the left. The supermacro was perfectly balanced! (I said 'was' because I no longer have it).
The second thing I noticed was how light it is compared to the supermacro. The SM feels like a small brick that you could throw for self defense if someone tried to mug you. The portaphile doesn't feel like a brick at all.
I think I like the construction slightly better than the supermacro. The volume knob is very tight, so you don't have to worry about accidentally turning the volume if you put it in your pocket. I'm relieved to see that the volume knob is now at the right, not at the center in-between the jacks which looked ugly to me. The only negative thing I can think of is the 9V battery straps. I hate straps.
So, what better way to compare sound than with the sr71? I played "Stuck" from Stacie Orrico's Live in Japan. I chose this song because the first time I listened to the SR71, I was struck (more like knocked out) by the punchiness and detail that the sr71 provided straight out of the box. It's like those drumsticks are hitting my eardrums directly!
Rather than describing what the Portaphile adds to the unamped source, let me describe what the Portaphile lacks from the SR-71's sound. The sr71 has more "air," and is slightly brighter. The bass is punchy, but not quite as refined nor as sharp as the sr71-- but not that far off. I can see why the review of the beta version mentions that it sounds closest to the sr71. The sound signature is very close-- quite neutral, and the Portaphile sounds very good with my HD580, SR225, and Ety er6i. I hate ety's for their shrillness and it seems that the portaphile reduces the shrillness-- I can't say for sure without more extensive listening.
I would've liked to compared this with the SM with 8610. As I remember it, I wasn't at all impressed with the 8610s in the supermacro. It sounded so flat and boring with almost no soundstage. Not so in the portaphile. This amp is definitely a keeper and at half the cost of the sr71, it gives other amps near its price range a run for its money. I can't wait to hear how the amp improves as it's broken in.