Review: Rhapsodio K2 Portable headphone amp

Review: Rhapsodio K2

First off I'd like to thank Rhapsodio for sending me this sample for review, I will write as honest a review as possible and the amp got over 50hrs of burn-in, no differences were noted.

Gear Used:
IPod Classic 160gb > DIY Pure silver LOD > Rhapsodio K2 > Alclair reference monitors/Final Audio Design Heaven VI

Battery:3.7V 1700mah
Output:150mW@32Ω (depends on opamp in use)
Run time:24+ hours
Charging method:Micro USB cable
Dimensions:21*51*83mm(excluding the knob)
*voltage supplied to opamp : +/- 8.5 v
MSRP: $90

Build Quality and Accessories:
Packaging is not mentioned as i did not get this amp in retail packaging.

Build quality feels rather good, the casing is all metal and everything fits flush, switches at the back don't stick out so you won't accidentally switch it to high gain, and the volume pot is smooth to operate with a good size knob, not too big.
As this amp is made for op-amp rolling it is easy to open, just take either the front or back panel off and slide it out, the build on the inside is good, there are a few solder joints that could be better but overall very satisfactory.

Accessories that came with this particular amp are a micro USB charging cable and a short Mini-Mini cable, it would have been nice to see a small velvet pouch and amp straps but the included accessories are all the necessary.

Functions and usability:
This amp has a few small functions which improve overall enjoyment, first off we have low and high gain which is great, it won't power hard to drive headphones very well, but it means you get very little channel imbalance at low levels on low gain, even with uber sensitive CIEM's.

The gain switch has 3 positions, low gain, bass boost in the middle and high gain, this means that bass boost is only available in low gain mode, the bass boost is good if you want a slight increase in the lows but for my liking it affects the mids too much, making the mids too warm.

Next to the gain switch we have the power switch which also has 3 modes, off, on and external power, which lets you use the amp solely from external power without charging the battery.

As previously stated the volume pot is smooth to operate and has very little channel imbalance even at low listening volumes. The input and output jack sockets are far enough apart for jacks on the larger side. The form factor is good except it is a little on the thicker side, but with the caps and everything on the inside you can see why it is that size.

This amp was made for op-amp rolling, the faceplates are easy to remove and the amp just slides out of the housing, it has op-amp sockets and will accept dual or mono op-amps, it comes with a JRC 4556AD op-amp pre installed.

Listening done on low gain bass boost off

The lows stock are not the tightest and sound a little sloppy, it sounds like they can't keep up with the music and also like it has a mid bass hump. The JRC 4556AD is a good budget op-amp but in the lows it shows it is lacking slightly. Detail is fine but in terms of articulation the lows are too rough and harsh, not tight and smooth like my C5 or O2.
I am making the lows sound very bad, they are not really bad I just think they can be improved on (which is coming later in the review).

Mids are fine, fairly detailed and transparent they portray the mids realistically with no peaks or harshness. Obviously they are not up the in terms of natural sound and detail with the O2 but for a budget portable amp the mids sound fine with separation also well portrayed.

Good extension and detail but the presentation is a little laid back, which is good for longer listening sessions without fatigue but it doesn't have the fun sparkle of a more aggressive sounding amp.

Stock this amp fairs well against the likes of the E11, it has more detail and a more neutral sound, compared to the iPod's internal amp you get much better detail and control with a wider soundstage also.

Now lets swap that op-amp out for one of my favourites, the LME49720 NA

The lows gain better control and punch, you no longer get the slightly sloppy bass guitar. With the LME kicks sound more realistic as they have better body and the lows overall gain better precision and body.

Mids continue similar, this is where it's least affected but they do gain a little more detail but also sound a little drier, by no means do they sound clinical but they are not as warm as stock.

Highs gain more air and better control, but are a little brighter than stock which can cause fatigue for treble sensitive listeners.

With the LME the amp becomes very detailed, precise and balanced, stock it is a little warm and the LME takes that warmth away and gives you more detail and better control. Soundstage with the LME is a little wider than stock, but not a big difference, mainly there is more air between instruments.

Conclusion: Stock it's a great amp, you get bass boost and low and high gain, along with good form factor and build quality it's a winner. Now considering the fact that its easy to change op-amps, it makes it even better value, you can tailor the sound to your liking with different op-amps, go for a OPA2227 or similar for a lush warm laid back sound, or a LME49720 NA for a more neutral and detailed sound.
For $90 it is good value, better than most standard cmoys, and the Fiio E11, unfortunately I have not had experience with the BH C&C amp.

Tracks Used:
Skrillex – First Of The Year (Equinox) (320kbps MP3)
Paramore – Franklin (320kbps MP3)
Diana Krall – The Girl In The Other Room (FLAC)
Deolinda – Passou Por Mim E Sorriu (live) (ALAC)
Suicide Silence – Unanswered (FLAC)
Massive Attack – Angel (ALAC)
Eat Static – Dzhopa Dream (ALAC)
The XX – Crystalised (FLAC)
Funeral For A Friend – Bend Your Arms To Look Like Wings (ALAC)
Mumford & Sons – Little Lion Man (FLAC)
The Scene Aesthetic – Humans (259kbps MP3)
A Hero A Fake – Swallowed By The Sea (254kbps MP3)
Vivaldi – The Four Seasons, Spring Allegro (ALAC)
Johnny Craig – Children Of Divorce (161kbps MP3)
Deadmau5 + Kaskade – I Remember (Caspa Remix) (320kbps MP3)
Black Uhuru – Utterance (ALAC)
We Are The In Crowd – Never Be What You Want (226kbps MP3)
Silverstein – Discovering The Waterfront (320kbps MP3)
Concept Of Thought – Our Thought (FLAC)
Nirvana – Something In The Way (Unplugged) (ALAC)