Good sound is where you find it. You can't exactly make a sweeping generalization about vintage vs. modern, but you can apply a few principles, also knowing that just when you have formulated a rule of thumb, along comes a unit that defies it.
In general, modern amplifiers are going to be more aware of how to apply negative feedback in doses that improve linearity without damaging rise times and musicality. Also, in general modern amps will have wider bandwidth (again, translating into faster rise times and therefore better transparency) and wider signal-to-noise ratios.
But you also often find that the "audio classics" of the '70s and '80s share many of these traits such as high s/n, negative feedback applied in nests and with restraints, high current and low output impedance, and wider bandwidth (translating into faster rise times and more accurate square wave response).
A great example of this is the McIntosh MC275, a 51-yr-old tube amp design with usable bandwidth out to 100KHz (and corresponding near-perfect square wave response), low noise, and low distortion. The Marantz in question has an outstanding s/n for its time (110 dB, competitive even today) and decent response curve--only down 1 dB at 60 KHz.
I have a couple of vintage SS amps, a VTL TransMOS 150 from around 1985, with very high damping factor, with very low output impedance and high current (it's stable into 0 ohms). It was a transconductance amp, taking advantage of MOSFET technology to make a transconductance amp with a signal path modeled after tube amps. The Acoustat/Hafler TransNova designs had a similar approach and a patent war over this technology. My TransMOS amps have deep, extended bass, great stability, and a sort of liquid presentation. The upscale Gold Edition was one of J. Gordon Holt's favorite amps in the mid-'80s.
And yet, I picked up a 1981 Heathkit AA-1600 bipolar power amp that kicks its ass in every way. Its specs reveal a wider bandwidth (out to 100 Khz) and excellent s/n of 100 dB. There is also the parts and build quality; the execution of this amp leaves nothing to be desired. I picked a refurbished one up for $239 and it trumped the VSP Labs handily--faster, more transparent, more neutral, no distracting SS glare.
Still...a couple months ago I heard a $999 Marantz PM8004 integrated amp powering a pair of $12.5K Sonus Faber Cremona Ms. This amp trumps most vintage amps and certainly 'most anything you'd find at or near its list price. It has an extraordinary s/n, especially compared to vintage amps--125 dB, and a nice wide bandwidth. It is dead nuts neutral with no detectable coloration and can drive a $12.5K pair of speakers to take your breath away.
So...vintage vs. modern? As always, categories have to give way to the merits of the individual units. The 1981 bipolar Heathkit beats the more "enlightened" VSP Labs TransMOS 150, and yet the modern $999 Marantz PM8004 integrated amp--complete with excellent phono stage, built-in low-noise line stage, pre-out/main-in, and bypassable 3-band EQ and balance controls--trumps them both along with countless other vintage amps.
There is also the personality factor. Some of the old Marantz tube amps are classics, with aficionados who love them for their largely unduplicated organic midrange purity at the expense of somewhat flabby bass control.
What to do about the Marantz 300DC? How does the price compare with other limited edition, carefully built amps with a 5-60Khz frequency response, outstanding s/n of 110 dB, plus the coolness factor of a 34-year-old design with those big meters that can still make beautiful music? Before you make your decision, try to listen to a Marantz PM8004, or any amp from their Reference series with the HDAM circuit
