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Portable Amps item created by nightmancometh, Jan 25, 2011
Pros - Powerful enough to drive 400i Hifiman
Cons - Dated by now
I found one cheap for 100 bucks and decided to get it for the balanced out capability. I already have a D7 Ibasso that I used on a nearly daily basis, so why not try out a PB2.
In stock form it sounded great from the single ended output. Swapped out to the WB 634 buffers and two Muses02. Great combo, but it was still lacking something. It didn't sound as nice as my desktop amp, which is the Zamp V3 with Burson V4 in it. I made an adapter for the Hifiman and man what a difference in sound in "balance" mode. Sound is twice as loud vs single ended. Soundstage has more depth, width, and clarity like Zamp amp. Ofcourse it doesn't play as loud as the Zamp, but you can't complain on what this little amp can do with the planars. Supposably it can output a total of 5W into 32ohms. IFI can do 4W @ 16ohms. Not bad for this old amp.
The nice part is that it comes with dummy buffers. Nice to have when you want know how your Opamps really sounds like. And like the Burson Lycan, you can test both single and dual opamps.
Power Source：Built-in 12.6V Li-Polymer Battery Pack, or 16V External Power Supply
32V voltage swing
Frequency Response: 10Hz~150 KHz -0.5dB
Signal to Noise Ratio：-115dB
Output power：Up to 2500mW+2500mW into 32Ω
Gain: +6dB/ +12dB/ +20dB (Balanced Output)
Gain: 0/ +6dB/ + 10dB (Single End Output)
4-layer gold plated PCB
Battery Life: >20 Hours
Battery Charge Time: 4 Hours Recommended. 80% when the red light goes off. 2 hours after that it's fully charged.
Has overcharge protection
When the furnished AC adapter is connected, the PB2’s battery is bypassed
Headphone Impedance: 8~600Ω
Case dimension: 2.2W x 3.9L x 0.95H (inch) 55W x 1001L x 24H (mm)
Weight: 168g or 5.9oz
I think 100 bucks is well spend on this amp. The Ibasso P5 cost way more and for the full potential, you still need to buy the stand alone PSU. I haven't had issues with short run time with my PB2 unit, even though it's a few years old already. Also using 9V batteries for a portable amp in this day of age, is just plain ridiculous.
Changing gain is a bit of a hassle, as you have to open up the unit to access the jumpers.
Wired up the TRRS plug like the pic below. This way I can still use the headphone in a regular single ended output. I found the pic here on the forum.
Ibasso D7 as Dac, feeding the Pelican directly.
I swapped out the stock 1200uf 16V cap and stuff in dual 1800uf 16V caps instead. Subbass is cleaner.
In single ended mode, I stacked the Buf634 with good results. Subbass got cleaner with the JVC SZ2000.
For fun I stacked the Buf634 WB on top of the Buf634 for balanced mode. Bass got better with the Hifiman, but doesn't sound as nice with just the Buf634 WB installed. The JVC SZ2000 got the same type of subbass boost, but didn't sound as nice as with the regular stacked Buf634. But you quickly forget about what you are missing once you start jamming away. The JVC's are powered properly now with the underrated Pelican.
Pros - Power, balanced/single ended output
Cons - Battery life
I've owned two of these now and it's time to write a review. One I bought new last year (and sold on here) and one I bought used on these forums. To put it simply, this is the best portable headphone amp I have ever owned or heard. I used this with a pair of Hd800s, balanced D7000s and LCD-2s. It easily powered all of these with authority. There are multiple gain settings as well, for more sensitive headphones, although you have to take the amp apart to change this. The little opamp kit this comes with is pretty cool as well, its really quick and easy to swap them out and fun to play around with different options. Sound from this amp (stock) is pretty neutral. I did many comparisons with this and my Schiit Lyr (out of the single ended output from the PB2) and I can honestly say that I could not tell them apart, this little amp can really power anything with some serious force! My one and only complaint is the ridiculously low battery life of this amp. I would say based on my experience that this amp has a realistic battery life of 5-6 hours when fully charged. But I guess that's a small inconvenience for such an awesome amp!