It is a good set....was very good at the time.
Technology marches on and this is no more true than with digital.
It is STILL a great piece and if you enjoy it, then be happy!
If you are looking to upgrade, there are a number of options. Since the 'day' of the P-1A/P-3A, we went through a period where we were principally modifying standalone players, SACD and Universal types. Now that computer audio is more and more popular and with the availability of hi-rez downloads, DACs are once again in the forefront and USB is one of the common ways to connect to your computer.
The P-3A is 24/96 capable however, and has RCA and XLR digital inputs, so you can still stream from a number of devices, such as Logitech Touch or Squeeze Box as transport, or you can purchase a number of USB - SPDIF/AES/EBU converters.
So, in a nutshell, technology has moved on and there are exciting things happening. The P-3A is still a great DAC. For more money, you can do better...such is usually the case in audio.
Take care,
Dan W.