Returning to the OP's question - it looks like you are going to need the drill trick after all. I had assumed that Sennheiser used the "standard" 2.1mm size, like Trantec, etc, but no. They do a NT2-UK PSU, which is 2.1mm, with a plastic "collar" at the tip (I have 4 of them, but no idea what they fit - Freeport?), but EW G1 & G2 (I don't have any G3 or G4) use a NT2-1, which is 1.7mm, with spring contacts, rather than just a tube. The original XSW uses a NT2-3, the XSW1 uses a NT12-5 & the Sennheiser ADU uses a NT1, but I can find no indication of pin sizes for these.
I suspect the Thomann is actually 2.1mm (which would suit most makes), suggesting the XSW is 1.7mm, but the only way to be sure is checking with 1.5mm & 2.0mm drill bits. Yes Ray, I did measure my drills first (all within 0.01mm of nominal).