Monrio Asty Dual Mono Mosfet replacements
I've got a Monrio Asty Dual Mono power amp that I bought a few years back for repair. It is a mosfet design using 2 pairs of 2sk413/2sj118s per channel. The right channel had a mismatch of outputs from (who else!) NTE.
The source resistors are 4 paralleled 1 ohm metal films, giving a grand total of .25 ohms. Thus the VGS matching on any replacements are going to have to be somewhat tight.
So I'm trying to decide a cost effective way to go about replacements. I can get 2sk413/2sj118 for about $9 a pair. But I'll need quite a few, or dumb luck to get where I need to on matching. I suppose I could bump up the source resistance to help with current matching.
I can get IRFP240/9240, FQA9P25, FQA28N15 devices for $1.00 to $1.50, with the added bonus of a much smaller VGS spread. There isn't much heatsinking though, so I don't know if I can get away with much increase in bias.
2SK1529/2SK200 are another option with a revised VBE multiple to accommodate the 50% lower required VGS. But again, I need many pairs at $8-$10 a pair.
Any suggestions, insights, obvious things overlooked?