The 1st generation Yaqin MC-10L's, from at least 14 years ago, had some issues, but later versions are quite excellent. The transformers are not small by any means.Did you open this one upas well to look inside? There was some buzz a few years back on the net about these amps having issues as well and possible issues with OPT's too as well as the Music Angel 845 amp. I was going to get one of these until I saw those posts, changed my mind about them. Went for the VTA-120 after I found out about that amp from a buddy.