Correct - the BP6 evolved from the B-60 chassis which is also aluminum. The BP-26 and the MPS-2 are steel chassis for both.
james
This is interesting, as I would presume that the aluminum enclosures would be premium in terms of cost and both heat dissipation and vibrational characteristics vs. steel.
Perhaps, since all of the Bryston amplifier enclosures are made of aluminum, and the BP6 is a spin-off the B-60R (an integrated amplifier) it acquired the premium aluminum chasis, whereas, the BP26, being the evolution of the BP20/25, inherrited an updated steel case - as the heat dissipation requirements are lesser for a preamp then an amp.
In any case - as I see it, the BP6 from this perspective would have a preferable construction - at least from a material standpoint. Guage of metal etc. could make this mut between the BP6 and BP26 - I would guess.