I am the owner of this amplifier and I like its features most. It has a Xfeed, Bass booster, 3dB Treble booster, a 75 ohms to compensate for too low impedance phones and a 10 dB booster that has been very useful to me. Also the programmable automatic shut off feature that works for 1, 3, 6, or indefinite hours. The quality is very good, but you are not expecting here a 1,900 $ phonitor, eh? It is outstanding for all kinds of music. You need to buy the rechargeable feature because the amplifier is too miniature to be opened every once in a while. You can also upgrade for a various number of ICs to see what of them suits you most. I have upgraded the IC several times for better sound. This is the amplifier for the newcomer or the experienced headphone lover. It moves a Koss PROAAT headphone using the 10-dB feature. I also moves many other high impedance phones like the Yuin PK-1 and all high impedance phones I own. Try to buy it through the distributor's web site (google to: XM5).