Sequential Tube Monoblocks

Vintage McIntosh monoblock tube amps- MC 30 or MC 75.
Is it important to buy sequential units?


You bet it does..

Tubes, resistors and caps were made with sequential batches.

Channel balance will be off if not.


Totally depends on the manufacturer, but it’s ALWAYS better to have factory matched pairs or at least consecutive / close serial numbers. Hand wiring will have more chances for variance than PCB, obviously. Some manufacturers will also make minor parts swaps or circuit changes over time. Sometimes parts swaps are a necessity since they regularly go out of production (specific transistors, black gates caps, polystyrene caps etc). 

VAC’s owner auditions every component before it leaves the factory. If it doesn’t make the cut, it goes back for tuning. You can bet there’s an advantage to having this process done for a pair of mono amps, rather than cobbling together 2 units on the used market (many of VAC’s amps are switchable between stereo / mono modes).