Quite the opposite amigo.
All that i post before doesn't apply at all to your v.3 buffer!The X-10v.3 is a completly different buffer! Musical Fidelity had made a very limited manufacturing of that unit. The new Mu-Vista tube is Musical Fidelity’s highest performance tube to date. It’s more linear and quieter, with better performance capabilities than either their highly regarded Nu-Vista or Tri-Vista 5703 tubes.

I know very well that buffer, because a friend of mine has one.
The 6112 valve it has, is an ultra high performance twin triode. Originally, it was used by the US military for crucial low noise guidance and other missile functions.

It is incredibly rugged and immune from microphony and other extraneous effects.
Also, and we hope this attribute is never needed; it's immune from electro-magnetic pulse (EMP) which occurs when a nuclear bomb explodes!

As you would expect, the mu-Vista is super tough, super quiet, ultra reliable, incredibly linear and absolutely predictable.
From what i know, Musical Fidelity has not had a single Tri-Vistor 5703 tube fail anywhere in the world in any of their Tri-Vista products. The mu-Vista has similar levels of reliability, and why not? The tubes have been purchased direct from the US military and are genuine milspec, mil usage parts.
BTW, According to the X-10v3 owner's manual "This product has been designed so that it may be left on indefinitely, it may become warm to the touch - this is normal."
Here some specifications:
* Input impedance: 470K Ohms
* Output impedance: < 33 Ohms
* Total harmonic distortion: < 0.004% 10Hz to 20kHz
* Frequency response: 20Hz to 65kHz +0, - 0.5dB
* Crosstalk: Better than 80dB, 20Hz to 20kHz
* Signal / noise ratio (reference full output): Better than 93dB unweighted
* Better than 106dB 'A'-weighted
* Valve (tube) type: 6112 twin triode (two)
* Power requirement: 12 - 0 - 12 Volts AC 500mA (via mains adaptor supplied)
* Dimensions (approximate): 180mm (7.1 inches) wide
88.2mm (3.5 inches) high including feet
218mm (8.6 inches) deep including rear terminals
* Weight: Unit, net 2.5kg (5 lbs 8oz) un-boxed, Adaptor, net 0.45kg (1 lb)
Total packed 3.1kg (6lbs 13oz)
Now, about the 6112 valve, please note that these MIL Spec tubes if left on indefinitely have a 100,000 hour life span if my calculations are correct I figure 11.41 years.

Hope this helps.
Have fun.