I have used the xvive u4 for monitoring with 4 member band but i was the only one who was using the xvive u4 but we were using it with a different wireless mixer which created some signal interference, as the xvive uses 2.4 ghz, changing it to different channel did solve the issue at that time. Also xvive does not do the automatic channel selection you might get away with selecting different channel manually if there is interference. Sound wise i will say it is a good mono signal. If you want another wireless system which is cheaper then you can look into NUX B-7PSM, i believe it uses 5.8ghz, it might be better. i have seen some good reviews in the internet but never used it. and i believe it does auto selection of the clean channel if there is any interference. I believe it is about $199 in amazon which is similar priced with xvive u4. i was also looking into the Phenyx Pro Wireless in-Ear Monitor System. see if you can find reviews on that as well and it is a stereo monitoring system.
Or you can always put drummer in a wired mix and rest of the band use wireless systems. this way you will have less device in the bandwidth.
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