SqueezeLite - pops and crackles when syncing with SB3s

I have two SB3s and SqueezeLite running on a Windows 10 desktop, all wired in. The syncing of SqueezeLite is usually out by a very noticeable split second. But more annoying is that the SqueezeLite causes crackles and pops in the SB3s, about once a minute. Presumably these occur as they all re-sync, but it only happens when SqueezeLite is sync'd. Is there a way around this, either by changing the configuration, or by using a different software player on my PC?

Configuration:
Windows 10 64bit, recently installed on a 2yr old desktop
2 x SB3s, all wired
LMS 7.7.5