I have been enjoying the Stereomour for about 3-4 years now. Everything works great until recently when I noticed the left channel is softer causing the stereo image to shift to the right. I have swapped the tubes L <-> R and the left is still softer. I have put in another set of 2A3 tubes and still have the same issue. I have bypassed the input selector and volume control pot and issue is still there. I have tried different source and still same issue. I put in a different amp and the issue went away so it sounds like it is an issue with the Stereomour amp. Some time the imbalance is not noticeable when first power up, but after a few hours, it tends to be more noticeable. Any help is appreciated.