Quality active speakers with Airplay and sub will do. Airpulse or Edifier. Phone or tablet with Spotify or Tidal over via airplay.

Edifier S2000MKIII, AirPulse A100, A200, A300. Add sub of your choice. Polk is good.

Buy a Hafler 100 preamp instead. Less expensive and much better sound. Then you can buy a Hafler 200 amp. I have this combination I bought for $300 from a local seller. Good stuff!

Those old Marantz solid state units from the 70's aren't worth the exorbitant prices some are asking. Instead, the tube gear that was built and sold when Saul Marantz owned the company is definitely collectible -  the model 7 preamp and models 8 and 9 amps.

I chased vintage Marantz receivers almost two decades ago.  Granted, $150 max would get you a Marantz 22XX series receiver in decent enough shape, but there would be an outlay of almost what you paid for the receiver to repair the receiver at some point down the line.  I stopped chasing.  Now you are talking electronics that are more than 50 years old.  

Consider buying new, consider the Outlaw RR2160.  Other than buying speakers, there's nothing else to buy and you have all the options you need.

I realize it is outside your budget ($1000 vs $600).  Then again, I have my Outlaw receiver since 2006.

Rich 

https://www.stereophile.com/content/outlaw-audio-rr2160-stereo-receiver

I am quite familiar with the Marantz 3300/3600/3800 preamps, and owned a Marantz Model 7 tube preamp for nearly 30 years. I also owned a Hafler preamp.

A new Schiit Saga blows all of them out of the park sonically. I use a Sylvania Bad Boy 6SN7GT in the original Saga and the sound is great.

why not build a system out of new Schiit gear? And if you want a complete system without tubes, the Schiit Ragnerak is on closeout at $999. You can put a multibit DAC in it for a few hundred more, and you get a headphone amp that ranks up there with the best as well.

I had Marantz (3200,140) gear in the ‘70s. It depends if you’re looking to make a system with fantastic aesthetics and decent sound or better sound.
 

A great combo for me a little later on in the ‘80s was an Advent 300 as a preamp and a Hafler DH-200. The Advent has a terrific phono section if you want to play records and the Hafler was a really clean power amp. Unlike the Marantz, these are not pretty components. They ugly. The Advent looks like a radio from 1958 and the Hafler is a rectangular block of dead weight. But they sound great and you can probably get them both for the same price as the Marantz.

I kept them both for 20 years before I was temporarily seduced by the dark side of home theathre (oooof aaah). Thank goodness that only lasted a year..

szeidman2002: I agree with your pairing! That Advent receiver - who remembers it today? - is a gem! It's pre-out made it quite versatile! Add the excellent phono stage - still competitive today! - and you have one of the best bargains in audio. 

Consider portability and compatibility along with sound quality. Old gear is best left to tinkerers and collectors to source for themselves. You didn't say how old your son is, but if he is in the peripatetic years in his 20s, compact, easily-moved 2 channel monitors and a reasonable sub and a one-box integrated amp with dac and streamer would be a good option. JBLs SA750 is that, but maybe out of the budget range. Cambridge Audio CXA81 and a WiiM Pro streamer would be an excellent budget-conscious option.

@jetson  I'd say option #3.  He he...consider Schitt for higher end reasonable cost.  Watch Cheapaudioman on u-toob for many other budget but good options.  I feel like we're all thinking you're wanting to keep the cost down.

I would look into a used audiolab 6000a.

Has a competent phono, it has a streamer and it sounds great ( many great reviews)

Search in H-F shark basically new units for $500

Think so many people miss the point of vintage gear. Audio brings emotion. Marantz is as much art/decor as sound. Many people are building up system that attain a certain look, with sound being a byproduct. 

yes, lots of new things might sound better, but they look like poop. 

I would rather have a vintage Marantz for $600 then something new. Nothing sounds as good as my vintage setup for the price. Plus Marantz has a certain sound that some just love, much like Mcintosh.