Localhost levels and s.volume

Questions
1

This might be a simple question - but it would be great to understand this better:
With s.volume, I can turn down the overall server volume. Is there any way to turn up/down individual channels at this node in the software? I was thinking about trying to modify localhost levels to simply have mute buttons, if that’s not too far-fetched.

2

Could you give the following code a try?
From what I’ve tested, the behaviour seems rather inconsistent.
I was thinking of raising an issue, but the inconsistency has rather put me off doing so.

{ [WhiteNoise.ar, SinOsc.ar]*0.1 }.play

v = s.volume
v.volume = 0
v.mute
v.unmute 

~v_ch0 = Volume(s, 0, 1);
~v_ch1 = Volume(s, 1, 1);
~v_ch0.volume = -6 // FAILURE IN SERVER /s_new duplicate node ID
~v_ch1.volume = -6 // FAILURE IN SERVER /s_new duplicate node ID
~v_ch0.mute
~v_ch0.unmute
~v_ch1.mute // mute ch 0
~v_ch1.unmute // unmute ch 1
~v_ch0.mute 
~v_ch1.mute // does not work
~v_ch1.unmute // does not work
~v_ch0.unmute
~v_ch0 = Volume(s, 0, 1);
~v_ch1 = Volume(s, 1, 1);
~v_ch0.mute // FAILURE IN SERVER /s_new duplicate node ID
~v_ch1.mute
~v_ch1.unmute
~v_ch0.unmute // FAILURE IN SERVER /n_set Node 3 not found

Also, this doesn’t seem to affect the s.meter.
I usually use Synth.set or Group.set instead of these.