The RA53b is a high powered headphone amplifier with five 1/4 and 1/8 (3.5mm) headphone and earphone outs. Two RA53b units may be linked together and mounted side-by-side in a universal rack tray for a total of 10 outputs.
Pros - Lots of inputs & outputs, Sound quality, value, American made, durable
Cons - No power button
Am I the only one guy on Head-Fi that owns one of these? This amp is fantastic and a steal at $90. Here is the first ever review to be made.
Build Quality (5): All metal chassis and input/output jacks are all gold plated. Build quality is superb and this thing has been used for over two years, it still works 100% perfectly. Even after dropping it on concrete twice and on my hardwood floor twice it still holds up and only had light scratches from drops.
Features (5): You get five outputs all with the choice of 3.5mm or 6.5mm. You have XLR inputs, mono 6.5mm input, stereo 6.5mm input, RCA jacks, 3 insert inputs and even line output. The line output is supposed to "join" two RA53b's together for ten outputs, but you can hook it up to any old stereo and it gives it a clean signal. I used this to drive multiple headphones, control a couple of speaker's volume, and give source to a second A/V Receiver. Lots of options here to choose from, very versatile.
Sound (4): Very flat, doesn't color the sound in any way, in other words, what comes in comes out. Little background noise is heard and it almost has a perfectly black background. The potentiometers (volume control) feel a little cheap, but they have good precision controlling the volume and only give off a tiny bit of channel imbalance at very low volumes. Gain isn't too much for your IEM's, but if you listen to very low volumes with IEM's, channel imbalance will drive you nuts. This is what caused me to take off a point. Under stress (Driving my HD 600, SM3, HE-400, and controlling speaker volume) the sound quality is still the same as if only one device was plugged in and doesn't degrade at all when multiple headphones are driven.
UPDATE 8-9-2014: I find that everything I said above still proves to be true after these past few months of using the RA53b. However, I will say that after getting more power hungry cans (HE560/500/LCD3), the Rolls does lack power. Clipping does occure above 60% with all 3 planars I listed. This amp can only deliver ~270mW per each side, which explains the clipping. It's a good amp for HD600/HE400 that aren't too power hungry.
Just like to point out, the picture is old. The new RA53b sounds the same as the old one, but the Rolls logo and color is white instead of red.