That M2 balanced looks a lot cheaper than the M3.
Looks also a bit empty inside too.
No balanced input , the name "balanced" comes from an XLR balanced output ( what's the use of it without any balanced circuit/input? )
Made in canada and with canadian transformers (no AN UK components inside).
They should therefore sound like the zero series rather than like the higher end M3/5/6... level 3 series.
Are you happy with your DAC2.1x ?