in ears wireless without hiss possible? and other Qs

[brutze]

Hi there

trying to get my vocal live rig sorted out.
I tried various sennh. in ear wireless systems incl. ew300 G2 (€600) and the G3(€1000), and it seems to me that the headphone amp on all of these was really noisey. Just switched on with the volume on the receiver at 0 generated noise.

I was surprised, and the sales team at the large european music store were also.

Am I expecting too much?

I tried the G2 in a live situation with the band and got whistling and interference issues at many frequencies too.

Can someone advise me here.

Thanks

PS
also thinking about...
Compression on vocals live. Does it generate extra feedback problems?
Recommend a good value eq for live?
I was thinking of using a portico compressor as dual mono for smoothing/punch duties.
Tuning: tricks for good inear monitor mixes? Artificial tuning a no-no?