I bought this product late November 2012 returned the next day of receipt for a sound problem coming and going on a speaker. By touching the volume knob on his return. A new product was sent to me by mid-December. Proper functioning but the symptom returns after 2 months. Left monitor off and a movement of the volume knob back on. So quality problem of the volume knob ... shoddy potentiometer (known issue on another forum buyer) His otherwise good for this price.