Denis, I'm not an expert on this and Ralph is certainly the best person to advise, but here are some thoughts. I don't see any reason why the phono output could not go into the tape monitor loop other than the possibility of the tape monitor loop not providing an adequate buffer to the load of the phono stage. If this is a problem, you'll hear it in the frequency response curve and the dynamics. (Ralph can advise best here.) Trust your ears on this: if you don't hear a problem, there is no problem. If you don't hear the frequency extension you're used to hearing with CD, then consider this a potential culprit.
As to the RCA-to-XLR adaptors, the major issue is the addition of another set of connectors/contacts, plus the quality of the adaptors themselves. I've heard that the BAT adaptors are of good quality, but I don't have any firsthand experience. The Walker Audio Extreme SST contact enhancer will help ameliorate the issue of the additional set of contacts, but obviously can't eliminate it.
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As to the RCA-to-XLR adaptors, the major issue is the addition of another set of connectors/contacts, plus the quality of the adaptors themselves. I've heard that the BAT adaptors are of good quality, but I don't have any firsthand experience. The Walker Audio Extreme SST contact enhancer will help ameliorate the issue of the additional set of contacts, but obviously can't eliminate it.
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