Musical Fidelity X10 tube buffer... tube life?

I have read the reviews saying the tube in this buffer is NOT replaceable? The tube was a special and unique type of tube that was made in a limited run and no more are available.
Is this true? and how long do they last?
Elizabeth -- Which version is it? I did some quick checking, and the X10v3 uses a pair of 6112's, while the X10-D uses a pair of ECC88's (which are equivalent to 6DJ8's).

Both tubes are available for reasonable prices from and, and undoubtedly from many other sellers of nos and vintage tubes.

However, I gather that at least in the case of the v3 physically accessing and changing the tubes may not be particularly easy, although it is probably do-able. It was apparently designed with the expectation that the tubes would either never require replacement, or be replaced by the factory.

The 6112 was designed for military use, and I saw a comment indicating that its rated life is 100,000 hours.

Best regards,
-- Al