My advice is not to use monitoring on critical recordings. It will affect the recording when you least want it.
I've used this setup for a long time. I disagree. It's completely optional to monitor on anything - critical ones or not. If I remember correctly, by not monitoring ANYTHING while recording, you are likely saving some power from the recorder's battery. However, I monitored everything while recording through those roland binaural mics because it was easy for me to find an ideal spot for, let's say, during an opening act and also for future reference. If the sound wasn't optimal, I could move around and figure that out while recording. Sometimes you just don't have that luxury of an opening act and just have the main act. Then it really becomes a problem because moving while recording could compromise quality - however if it sounds like shit from the start anyway, what have you got to lose? Do you want a recording that you know could sound better or just stick it through like it is? I always keep a pair of these on me, but I haven't used the mics in a long time because I found the bass from the recordings got a little heavy compared to good quality cardioids. That was an issue for me despite using a 12 volt battery box. I also don't think the earphones on the CS10 for playback are good enough because they also display more bass than others out there.
If you choose to monitor, then do what Ozpeter suggested - try to keep it at a reasonable audible level, but try to refrain from a full blast 30 on the PCM-M10.
One thing I would highly recommend with these - USE A BATTERY BOX and DON'T be reliable on the plug in power!!! They are more prone to Brickwalling / Distortion without it!
The PCM-M10's dial to level 4 recording, or at least close by it, via a line input battery box is a good "sweet spot" for me.
The one benefit I found with these that they are good secondary mics for my cardioids. I use them still for monitoring while recording on the cardioids and also as a backup just in case.
Also... I was slowly not becoming a fan of loud people around me anymore on binaural mics. Seems to happen more when I record. What gives? How do these assholes appear out of nowhere like that and magically stand next to me and no one else?
PS. another good thing about these mics is that you won't have to worry so much about them moving around on you. Sometimes that becomes a problem with these other cardioid clip-on mics depending on how they are clipped, which if they are misplaced somehow, it compromises the ideal stereo sound you wanted.
PSS. Also, don't use these mics with an Andrea USB-SA-1 at a loud concert. Bass gets way too exaggerated and near distortion. No ability to turn off the device's plug in power for true line in feeds.