Read the exchange in full. Mike retroactively requested a repair charge, blamed OP for using a faulty cable, and tried to upsell a $300 cable to OP, and then blocked his number after OP pulled Drew into the exchange.
I would not have been as patient or as reasonable as John. In fact, I'd probably have made a post similar to this the moment Mike tries to say that their $1,200 amp isn't designed to work with balanced LO with either the WM1Z or the SP1000. It's hilarious what audiophiles put up with when cheap production-grade gear have a massive amount of failsafes and protection circuitry.
While the 404 has a lower noise floor with the extra A&K ground going into the 3.5mm input on the 404, it will work just fine on the single 2.5mm TRRS and Masuda has confirmed this with me. Granted, the 404 doesn't have as much output power as the WA11, but they're in the same ballpark IIRC.