I agree with matt that the sound will be different. In fact, it will be completely different.
Your current rig is the DLIII Dac. This is an aging DAC, but it is very well designed with a very good power supply. It is a conventional DAC chip with a fully discrete Class A I/V circuit that uses FET inputs and bipolar outputs. This going into your XP10 preamp, which is also fully Class A (and I also think this uses FET circuits). Finally, you’re going into the XA30.5, which is 100% Class A at 30 watts.
Three stages of Class A circuits in the analog path will create a very warm and full sound. It will be very listenable with absolutely no listening fatigue. However, with that many Class A stages, you’ll start to lose resolution, attack and there will be a slight roll-off of high frequencies.
The DirectStream Jr is a completely different beast. It is not a conventional DAC. It uses FPGA to analyze the incoming digital data and formulate how the output is generated from multiple voltage rails. The final voltage output is through a high-speed Class A video amplifier (video amps are extremely fast slew rate, so it is not like a normal warming Class A circuit). The idea behind the DirectStream is to make the signal as 100% accurate as possible. The end result will be significantly more resolution, attack, detail. It can reveal more information in the sound. However, when poorly matched with other equipment, it can be too solid state.
Since your amp is a full excellent 100% Class A amp, the DirectStream Jr. might be a good solution if you are looking for more resolution and accuracy. There will be no coloration added to the sound signature (unlike your DLIII/XP10 combo).
Your existing DLIII and XP10 are FET based and will add a richness and texture to the sound. This can be extremely pleasant, but it is not necessarily accurate to your source. This combination will also be more warm/thick sounding.
Neither is really a bad choice, it all depends on the direction you want to go in.
