If you like your Pagoda, and if you haven't noticed and bothered about its laid-back and slightly unresolving sound, I would recommend another NOS DAC, like Audio-gd DAC-19, Metrum Octave, or another MHDT device. The Delta-Sigma stuff doesn't render the tone colors as rich and natural as the NOS DACs do, and most DS DACs have this terrible treble glare that can be very fatiguing (depending on how sensitive you are). On the other hand, the DS stuff is much more dynamic and more resolving. But I don't think these are important to you since you haven't thrown the Pagoda against the wall already (?).
If you still wanna try out a Delta-Sigma DAC, I personally would recommend to look into DACs with AKM chips (Emotiva DC-01, Fostex HP-A8, Hegel HD12, NuForce DAC80, Schiit Gungnir), maybe M2Tech Young or NAD M51. At least that's what I have been considering in order to break free from my a tad too laid-back Metrum Octave. However, I didn't consider them to be an improvement but rather a sidegrade with another configuration of drawbacks and advantages, with the problem of treble glare spoiling the music. The real good stuff would be above your price range.