Yoby is correct. Differentially-balanced designs (Ayre, Krell, Classe' Audio, BAT, etc) are the correct and optimal method of deploying 'balanced' signal technology. Inexpensive equipment with XLR inputs and/or outputs (often called 'balanced') frequently uses cheap op-amps to convert their single-ended signal to 'balanced' and these op-amps normally hurt sound quality. For this reason, it may indeed be best to avoid using the XLR inputs and outputs of inexpensive equipment, instead using the single-ended RCA connections.
However, some of the principle advantages of using 'balanced' (XLR) interconnects are still there even in non-differentially-balanced systems. Namely, the reduction in noise vs RCA-type interconnects, especially in long runs. Also, XLR interconnects are less vunerable to hum.
I find it puzzling that Metralla is so negative toward 'balanced' equipment, yet he has a BALANCED AUDIO TECHNOLOGY PREAMP that is fully differentially-balanced.