10μA anode current can sound very nice

For example the 1H4 used as a microphone booster amolifier with floating grid or at space potential.


http://euroelectron.blogspot.com/2018/07/1h4-with-grid-at-space-potential-mic.html


Other example the Pleiades V1, the CV2269 operated at even less anode current but with just an AAA battery.


(See also:


http://euroelectron.blogspot.com/2018/08/the-grid-space-potential-increases-when.html)


The advantage of such a low anode current is that internal electron tube output resistance is increased. So bass heaviness is eliminated by the output transformer primary input inductance. The sound is approaching natural or flat frequency response form producer's brain to listener's brain [Lowe, Morgan].


Flat frequency response from producer's brain to listener's brain, Sound Picture Recording and Reproducing Characteristics - D. P. Lowe, K. F. Morgan - JSMPE