No amp. Unplugged ... and scales and improv. every day.
I used to use a metronome for the middle 20 yrs. or so. I spend enough time now recording to click tracks that I don't need the metronome practice anymore.
I actually never began needing it until I started to play with slightly warped drummers and now that I've given that up, along with other mind altering pastimes,
my internal clock is back to where it was when I was playing big band and combo trumpet (1957 to 1969) ... sharp as the edge of a thin razor blade ... yet just as flexible.
I used to use a towel and put it a bit of it over the metronome, turn it this way and that, to get the balance right.
I've gotta be able to balance dynamically with the click ... i.e. be able to get louder than the click just by picking harder ... but also be able to get softer than the click by lightening up.
If I can't get than dynamic balance, then the practice is somewhat useless.
Time is relative to distance and volume, and is subjective, in the sense that it is our *perception* of time, that is needed to interact with the time source, or other players.
I need to balance (my volume ... my perception of the relationship) with the click, or with any time source, or other player, in order to find the pivotal point ( within self ) that is the organic internal clock. The other players need to hear me as well but I need to balance for my self, first, or I'll be useless to the others.
Of course the perception of balance is subjective also.
If you work with it long enough I think most everyone will see that playing accurately with an absolute time source is impossible.
That is where the flexibility and dynamics come into play. "Playing around the beat" is the ol cliche'.
How closely one can dance to the absolute click is an interesting thing to toy with.
The feeling is in the space between me and the absolute source, or when playing with real players, between my time and their time.
In the gap ... in the space ... how we push and pull ... there is the energy.
Release times ( how long is the note and how the curve of release times can change during a phrase ) are also very facinating to me.
What happens in the silence between notes is just as important as the notes.