Hi, redquilang!
Watch out -- here's one of my wordy information pieces. I hope you find some of it useful or interesting.
A LIMITED PRIMER of QUALITY PORTABLE AMPLIFIERS:
To help us offer you suitable recommendations, it would help if you could offer some information.
What is your budget? How much is your comfortable spending limit?
How you will be using your amp and phones. Will you be use them as true portables outdoors, in trains/planes/cars/buses? Will you be using them more at work/school/home... with some in-transit use?
Do you prefer a small amp for greater ease of carry?
Is it okay to carry a larger portable such as the Headroom MicroAmp ($299) or Larocco Pocket Reference II ($479+$35 US shipping), both of which sound great but are significantly larger than the small portables?
http://laroccoaudio.net/pocketref.html
The PRII has a unique sound that is usually described as very neutral, and it has a separate bass control that ostensibly does not adverse impact the rest of the frequency spectrum. I've only heard briefly a couple of times, but I also felt it had a sort of neutral signature. Definitely non-fatiguing, though I need to get a longer listen. It is very nicely crafted, is finished in a very solid case, and is at the largest end of the portables, as is the next amp. It uses 2x9V batteries, has an external AC adapter & internal charging capability. New is the separate PSR regulated, international power supply (120-240AC) -- $479.
http://www.headphone.com/products/he...he-micro-line/
The Headroom MicroAmp is a similar size to the PRII, takes 2 9V batteries, has a separate A/C power supply/adapter but no inline charging. I wouldn't want to use it as a portable (though many people do), since it is at the largest end of the portable spectrum -- but it is easily transportable and I love it as a desktop amp at work. Both the MicroAmp ($299) and MicroDAC ($299) eat batteries (2x9V batteries each) faster than some of the small portables -- though the MicroAmp & MicroDAC are more energy-efficient than the earlier Overture and Coda. The basic Micro module gets the best battery life. The Desktop Module gives better sound but shorter battery life (see the site). Sitting on a desk or nightstand with its power supply, though, battery life is not a concern, and it's a very musical, very enjoyable amp that's well worth hearing, whether or not it suits your immediate needs. It's got a wide soundstage with very good depth, excellent separation of instruments, fine detail that describes the unique sound of each performer but doesn't incite headaches with edgy excesses. It has a lush musicality, and the MicroDAC gives it added punch and even more dynamic range. Headroom is an apt name, since this amp has enough signal-handling power to let the music breath effortlessly, which is difficult for the smallest amps to achieve given the limitations of squeezing quality into tiny cases.
In fact -- as you get more comfortable here, try to get to any headfi meets that may be at least somewhat near you -- and get to listen to as much gear as possible. Many vendors have 14- to 30-day return policies so that you can return a piece of equipment if it really does not meet your expectations.
Despite everyone's best efforts to make recommendations, your decision comes down to what actually sounds good to you, or at least sounds best to you within your budget. Listen to a lot of different equipment -- and then trust your own ears and preferences.
If by portable you just mean something that relatively easy to transport back and forth to work or school, or whatever -- and hear along the way -- then the Headroom MicroStack (MicroDAC+MicroAmp) or some other Headroom configuration is certainly a great choice. The MicroDAC has ports/jacks for USB and Toslink Optical Digital for use with PCs and Macs and it enhances the sound of pretty much any amp. As has already been posted, to use the DAC in transit, you'll need a player with digital out -- obviously not an iPod (at this time). Without digital out, you can use the lineout from your player, connected to an amp. There are some nice options available to connect lineout from iPod or other player to the amp: LineOutDock (Audiolineout.com), SikDin, PocketDock, etc.
If you're NOT going to use the amp in really noisy places and want a very refined amp that's much smaller than the PRII and MicroAmp (though a bit larger than the smallest amps), Ray Samuels SR-71 ($395) has a very open and refined sound that's especially beautiful for Jazz and Classical, but works well with most music. It does have good Low-Frequency extension as well, though some feel that though the LF info is there it has less bass energy and impact that some other amps. It uses 2x9V batteries but it does not take an AC adapter and has no inline charger. It is a little bigger than the smallest amps. Some of its unique qualities are its huge "air" around instruments and performers, ultrafine detail and nuance, excellent timbral presentation, a wide soundstage and very quiet blackground.
If you prefer a really compact, truly portable amp, there are still several good choices among the better quality amps. You will find some members recommending XIN SuperMacro-IV with OPA2134 chipset default($349.99+) or SuperMicro amps. They're at the smallest end of the portable class and many users love them. The early versions were not my cup of tea, but the current amps are very popular. I have not been able to get hold of his recent versions to audition, so I can't offer any comments about them. Xin's even tinier amp is XIN SuperMini-IV with AD8397 chipset default ($199.99+) There are too many options -- for both amps -- to include here, so go to the site to learn about them:
XIN SuperMacro-IV Order Page List of Options
Ray Samuels' smallest amp (at this moment) is the Hornet ($350 with 12v AC universal adapter/charger included), which is really pocketable (as are Xin's amps) and has a superbly finished, custom-crafted aluminum case, external lo-hi-medium gain switch (flush with case so it won't accidently switch in transit, thus avoiding serious ear damage with In-Ear Monitors), has an internal charging circuit (NIMH batteries only -- no Lithium rechargeables allowed), and comes with a compact AC adapter ("wall wart"). It has a warm, smooth, intimate sonic character that Ray designed to be reminiscent of the close/intimate/warm-toned analog vinyl sound he is quite fond of -- a sound that is intentionally very different from the SR-71 -- and, moreover, performs excellently in its intended purpose as a truly portable amp. The midrange is somewhat forward and rich in tone and texture, and its bass is very big and impactful -- so that the sound very effectively cuts through background noise clutter to allow you to hear the music. Since it uses a very high-capacitance 15,000 microfarad capacitor, it literally requires 300-350 hours of burn in (play) time for the sound to mature. Out of the box the low frequencies are not developed, the top end can be noisy/edgy/fatiguing, and it's lacking in instrument separation and open spatiality -- all of which improve significantly with the long burn in. When mature it's capable of huge bass, smooth highs, rich mids, clear sense of space around performers, etc. It produces some of the most satisfying vocal presentations, recreating the full throat and chest resonances that most amps fail to achieve. Similarly, it paints a more realistic picture of the full body/case of instruments -- especially wood instruments, whether it's grand piano, guitar, violin, harp... Again most amps present upper or lower frequencies more prominently, but don't adequately present those frequencies that give body to people and their instruments. It's most dissatisfying to hear the complex upper components of guitar strings -- tantalizingly rich and complex -- only to wonder where the guitar's body is. The Hornet gives you the whole instrument. It's not as upwardly extended and doesn't give as much upper end detail and texture as some amps, so if it's HF detail you want, this may not be the signature for you.
Another favorite of mine is the Portaphile PV2^2-LT1210 Maxxed ($244.95+$4.05 US shipping/$12 Intnl shipping). 12-15v AC adapter not included) -- uses single 9V battery, external AC adapter, no internal charging (new "Shohin" will have internal charging). This amp has been developing gradually over the past couple of years, and this latest advancement is a marvelous step up. Though the casing is standard Hammond extruded aluminum -- ho-hum compared to Ray's deluxe instruments that feel delicious to hold -- the Portaphile has a great sound and is a very respectable audiophile amp. The stock casing and treatment keep its price lower than the Headroom and Ray Samuels amps, and it's sonic character is quite different from all the amps I've noted. While it doesn't have the lush, rich midrange and full-throated voicings of people and instruments, the PV2^2-LT1210 has very tight low frequencies, nicely extended highs, and really excels in imaging and a big dimensional soundspace. It's upward extension allows it to present more spatial and ambient cues, which creates a more immersive sound field. Its HF detail allows it to present percussion instruments with great definition and definite musical notes, as opposed to the usual click/swish/whack most amps portray. Cymbals and tympani strokes sound like distinct musical notes.
Here's one of those may cases where I wish 2 products could be combined. I'd love to hear an amp that combines the Hornet's rich, full, warm voicings and small gorgeous craftmanship with the latest Portaphile's HF extention, definition and great imaging. We'll see what new amps come up in the future. Portaphile has its proposed "Shohin" amp, and since Ray is always creating and developing wonderful things (I heard his dynamite "B52" amp at the National Meet!!!), I'm sure we'll see new small creations from him soon enough.
Although I don't prefer it, the Headamp AE-1 ($349) is very popular and had a solid, finely finished, custom crafted aluminum case and, as with Rays amps, Justin's worksmanship is truly excellent, if different in approach. It has a spectral balance that emphasizes the upper frequencies, and I to my ears it has a mid-bass hump and some other characteristics that don't fit my tastes -- but again, it is very popular and it has great speed and impact and excellent separation of instruments. There is a new version that may be coming out soon with a very different, glossy look (various color schemes?) that's fun, and I expect it will have sonic improvements as well. I'm looking forward to hearing it.
(Photos would be nice, but I have no more time just now.)
