I've serviced a bit of vintage gear and one thing I've noticed is that quite often if you really want the solid state stuff to work properly its going to cost a lot to make it happen- often more than tube gear. This is because there are a lot more electrolytic caps in both the power supplies and the signal path and in addition to that, the semiconductors often don't meet spec anymore due to corrosion.
I'd not realized until recently how insidious that last bit is- semiconductors gradually lose their Hfe (gain transconductance) and can become noisy or spitty. These days finding subs that actually work in the design can be challenging as there are so many counterfeits on ebay and the like. A few days ago I had an amp that only made about 1/2 power before clipping- but it was caused by voltage and driver transistors simply having degraded to the point that the amp didn't have enough gain for the feedback to work properly at full power. This was after I had literally replaced all the electrolytics in sight. That amp was allegedly working when purchased! Yet it turned out the repairs were far more than the amp was worth fully rebuilt.
So (counter-intuitively) its actually easier to properly refurbish tube equipment as a result.
I'd not realized until recently how insidious that last bit is- semiconductors gradually lose their Hfe (gain transconductance) and can become noisy or spitty. These days finding subs that actually work in the design can be challenging as there are so many counterfeits on ebay and the like. A few days ago I had an amp that only made about 1/2 power before clipping- but it was caused by voltage and driver transistors simply having degraded to the point that the amp didn't have enough gain for the feedback to work properly at full power. This was after I had literally replaced all the electrolytics in sight. That amp was allegedly working when purchased! Yet it turned out the repairs were far more than the amp was worth fully rebuilt.
So (counter-intuitively) its actually easier to properly refurbish tube equipment as a result.