The DIP Combo is a new update/improved version of the DSP, a design by C.C.Poon ten years ago and licensed to GW Labs for marketing. GW Labs is now defunct and Monarchy/C.C.Poon will service/update old DSP products. For details, contact Monarchy. The DIP Upsampler is a manual version of the Combo--you have to gain access to the internals and set a jumper to upsample versus flipping a switch with the Combo to attain the same affect.
All the original reviews (attached here)and comments on the DSP apply to the new DIP Combo, with an important exception:
"The difference between listening with the Combo and without was like taking off my loudspeaker coverings, it just brought me that much closer to the music. This was not a one trick pony as it did not just improve upon one area of the music but rather many, which added up to a very enjoyable experience."
"With the Combo aiding my CD player, now turned trans- port, I felt as if I had moved much closer to the performers. Background singers as well seemed clearer and closer to my listening area and the sound of the bass seemed less thin and took on extra weight. Soundstage was much improved as there was more depth front to back and the timbre of the saxophone was more accurate. A sense of imagery within the soundstage also increased and with this new sense of weight to instruments I started to enjoy this CD as never before."
- Anthony Nicosia, Affordable Audio
The Stereo Times Review: "GW Labs has come up with a product that addresses some very real problems quite effectively. While I found the 44.1 kHz setting made subtle improvements in my system, the 96 kHz setting is where the full capability of this DSP is realized. While $400 is not a great deal to pay for a component in the realm of high-end audio, I found it a reasonable price given the level of performance that the DSP offers."
Read the full The Stereo Times review on the DSP (PDF)
Head-Fi GW Labs Review: Despite my lack of enthusiasm over the upsampling, I'd recommend this unit easily (with the caveat that buying from a place with a good return policy is always a good idea with this type of device). This is the fourth jitter reduction device I've used (others were Theta TLC, Monarchy DIP Mark II, Monarchy 24/96), and the GW Labs DSP is IMO far better at cleaning up the digital signal than any of the others I've heard. The increase in digital signal strength is also a big plus...some DAC's, in particular the ART DI/O, that may have trouble locking on to a signal will have a much easier time with the boosted signal. Using external sync, my DI/O was able to grab and lock onto the signal much faster than it has been able to at any time in the past, with any source. That's worth the price to me right there (list price $399, demo unit at Audio Advisor was $229).
Read the full Head-Fi GW Labs Review (PDF)
Home Audio Review: If you're happy with your transport and DAC but long for an even more analog-like presentation, the DSP can certainly deliver the shot in the arm that many audio rigs need every so often to keep their owners excited.
Read the full Home Audio Review (PDF)
Audio Express Review: Strictly as a jitter suppressor and upsampler,
the DSP is hands-down superior
to Perpetual Technologies’ P-1A, and
at a fraction of the cost. I...The DSP
is an excellent product, at a very fair
price, and is highly recommended.
Read the full Audio Express Review (PDF)
Audiophile Audition Review: The DSP enhances the digital signal from the transport and then outputs this cleaner signal to the DAC. Multiple filters suppress noise generated within the unit and prevent mains-borne AC noise from entering the circuitry. The DSP boasts over-engineered power supplies. Separate transformer windings feed two low-noise rectifiers, followed by choke filtered capacitor banks - each with 20,000 microfarad filtering capacitance. The unit is designed to be powered on continuously and only unplugged when away for prolonged periods.
Read the full Audiophile Audiotion Review (PDF)
Affordable Audio Review: If you are looking to
take your system to the next level of sonic performance, then consider the quality of AC you are providing
your stereo with. You may be pleasantly surprised at what improvements can be coaxed out of
your current equipment.
Read the full Affordable Audio Review (PDF)
Bound for Sound Review (PDF)