The 501 and the Borghese are not a good match. The Bluenote arms are true unipivots with no kind of stabilization whatsoever. Just an inverted cup resting on a point. The compliance of the Shelter is too low for this type of unipivot arm. I tried the 501 with the Borromeo, and while it sounded ok, it was not an ideal pairing. You should consider another arm if you are set on buying the Shelter.
Oz
Oz