Amp Input impedance - old Macintosh C-20 preamp with modern SS amp

I have a pair of old, beloved friends in my system, my Macintosh C-20 preamps.  I've owned  them for over 40 years - they have been upgraded and very well maintained.  They sound wonderful.  I wouldn't part with them for anything.  They have been hooked up to a pair of ADCOM 5500s, which is a match I just love.  Some very recent developments have caused me to start thinking my ADCOMs might not be long for this world.  In the past two years I have lost two excellant local repair shops and I'm now faced with shipping my amps from Milwaukee to either Wyoming or the east coast anytime one them has a hiccup.  And lately, they have started to hiccup.
 
I would need two amps for my system so that limits me with what I can afford.  I was looking at the Parasound 2250s as my most logical choice.  My question regards output / input matching of the preamp & amp.
Number 1 - Does anyone know the output impedance of a Macintosh C-20 preamp? All I can find about the output are these two pieces from the old, 1960s manual:

MAIN OUTPUT 2.5 volts with rated input
    and this
MAIN Output Connected to Power Amplifiers
The MAIN and TAPE output jacks are fed from cathode followers. The input impedance of devices connected to these outputs should be 50,000 ohms or greater, and the capacitive reactance of audio cables connecting these devices should not be less than 8,000 ohms at 20,000 cycles. This is the reactance of a capacity of 1,000 mmf. Audio cable having a capacity of 25 mmf per foot may be 40 feet long; 13.5 mmf per foot cable may be 75 feet long

My ADCOMs were 49,900 ohms a good match, but many of today's amps are rated at 33,330 ohms.

Number 2  Long term /short term is this a mismatch? Parasound has a network of dealers including a few around here. Before buying I plan to take my C-20 in and try it together with a 2250; but are there other considerations, maybe long term, that could impact my decision?

My speakers are Magnepan 1.7 s, they are played at a robust volume level, and no, I can't swing a pair of big Parasound A-21s.

Thanks
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