It's quite reasonable to use a cd player. The Quad is quite nice for an older, devalued piece. The Quad could also support both direct and variable outputs so you would not need a preamp. Be cautious as the first gens had unreliable transports. Later gens were fine.
That being said, in general the newer dac's on the market are quite a bit better than most of the CD players with digital inputs that I have heard. They simply have better chips and some fairly nice dejitter technologies.
A note on the apple tv as a high falutin music source. If you are using an older model that had the hard drive built in, you will get a little better sound from the hard drive. The newer model that is streaming only gives audio sound with a fairly high level of jitter. This is due to the network jump.
Disclaimer-I have ties to av industry.
That being said, in general the newer dac's on the market are quite a bit better than most of the CD players with digital inputs that I have heard. They simply have better chips and some fairly nice dejitter technologies.
A note on the apple tv as a high falutin music source. If you are using an older model that had the hard drive built in, you will get a little better sound from the hard drive. The newer model that is streaming only gives audio sound with a fairly high level of jitter. This is due to the network jump.
Disclaimer-I have ties to av industry.