Squeezebox is probably, the best networked audio player on the market. I fall in love with it instantly — the ease of use, the beautiful VFD screen and elegant designed case, the feeling of all your music in the finger tips. In fact, I haven’t touched my CD collection once since I digitalized them into lossless FLAC format and stored in the squeeze center.
The only complain I have, is the sound quality from the two channel analog outputs in the Squeezebox classic and duet, it left much to be desired.
My vintage Sansui AU-D707F stereo amplifier and Squeezbox
My setup is quite simple, a 2 channel stereo amplifier to a pair of 200W louder speakers. The squeezebox is connected via analog connections. Although squeezebox claimed to use high-end 24bit DAC and special designed circuit, the analog outputs still sound relatively weak: it just doesn’t have the clarity and strength as my old sound source, an aged Marantz CD Player. So my pursuit to better sound begins.
My hand made linear power supply
The first thing comes to my mind is the power supply. Squeezebox comes with a cheap, small switching power supply. You know how bad the switching power supply will do to the sound quality, no matter how hard you try to regulate it (as squeezebox claimed), the electrical noise & ripple will still be there. On the contrast, Linear power supply can be up to 10,000 times quieter than switching power supply.
Notice the electrical ripple difference
I ordered a 5V linear power supply and replaced the old cheap switching power supply. It did improve the “strength” of the audio signal, the bass is much more powerful now. However, the sound is still lack of clarify and depth.
Naturally, the next step for me is to utilize the digital audio output on the Squeezebox — I don’t want Squeezebox to handle the “digital to analog converting” job, I want something else. Since most stereo amplifier doesn’t come with digital audio connection, the only possible solution will be a good quality standalone Digital to Analog Converter, in my case, the Maverick Audio Tube Magic Upsampling DAC ( What else can I choose? It’s my company’s own product 
). After I hooked the DAC into my setup, I immediately found the clarity of the sound has improved a lot, I can hear a lot more details than before. The overall sound quality is more transparent, natural and with better bass/tremble. It is really close to the sound when I was using my old school CD player, I can hardly to differentiate the difference between my old CD player and FLAC music played from Squeezebox. I can say the result is very pleasant, I can finally let go my old CD player without missing the sound quality.
I have had the same experience with an Apple TV as the music server. The basic line outs on these type devices just are not high fidelity. The Tube Magic D1 DAC is so much better with either the solid state or tube output that with lossless or WAV files you can actually do some critical listening. It is very close to a good CD player. I used the D1 with my computer at work for a couple of days to accelerate break-in and was really surprised that the USB DAC+headphone output sounded better than my NuForce Ikon mobile.