Hey all! I apologize up front: this is kind of long. I hope it makes sense. I made a recent thread pertaining to tube biasing, and I got very helpful responses; this thread, however, is sort of an extension or explanation of that. I’m struggling with a channel imbalance on my amp (Antique Sound Lab MG SI 15DT). The right channel is noticeably—not grossly, but nonetheless noticeably—louder than the left. At various peaks, the difference—per the Decibel X app—is several decibels. I have tested numerous records of several different genres (jazz, soul, blues, electronica), and the difference seems relatively consistent. Now, I have contacted my turntable’s makers (U-Turn Audio) and followed their isolation strategy for the turntable (reverse RCA cables) and the imbalance did not switch channels; therefore, I was told, the issue is not the table. I trust their judgement, but am ultimately open to other ideas from y’all, of course. Some more info: this imbalance also occurs with CD’s played by my Onkyo player; I have switched speaker wires; I have, in fact, switched speakers. All said, this makes me the problematic component is the amp. Therein lies my problem. HOW to troubleshoot? As my earlier thread mentioned, the power tubes (not the preamps, just swapped them) are very old. Could they be the culprit? I hope so honestly; that’s an easy fix. As a workaround—if the tubes are the problem—could I bias the weaker channel tube a little hotter than the other? Would that correct it until I replace these old old tubes?