The right vintage amp will beat anything based upon the investment requirement. It is not like an automobile where technology has improved performance and the value ratio between new and vintage favors new.
The reason, the "golden age" of analog is NOT 2006, at least not yet. It was in the late 60's through early 80's. The best equipment built then focused on analog and 2-channel stereo. Check out the internal components and build quality used on equipment such as McIntosh, Yamaha, Marantz, to name just a few. You will find everything down to the capacitors still superior by today's standards. With some minor adjustments and replacement of some caps the better vintage amps will perform like nobody's business. Maybe even replace the power cord. (THERE ARE GOOD TECHNICIANS WHO DO THIS.) This includes the phono stages in the preamps. Change out capacitors to say, black caps, and WOW! Good deal and fun to own!
This is a simplistic response but it's on point.