I bought an iDEA a couple weeks ago and have been impressed by its value. Compared to other SABRE9018Q2C-based USB DAC/amps (i.e. NextDrive Spectra, Cozoy TAKT Pro), it's the least expensive (discounting the near-identical Sabaj DA2), and seems to perform up to par.
I just noticed that SMSL have a dual-mono version of the iDEA, called the IQ, that's only visible on the Simplified Chinese version of its website:
http://www.smsl-audio.com/cn/productshow.asp?id=142
Because it uses a balanced topology, the IQ now offers balanced output that accompanies improved power delivery (55 mW vs 35 mW into 32 ohms on unbalanced outputs), lower THD+N, and thus improved SNR & DNR.
The Silicon Labs multiclock generator for MCLK is now replaced by two discrete TXCOs for 44.1 and 48 kHz multiples. Perhaps it'll be a little better performing in terms of jitter reduction, but I don't know if the change will be noticeably audible.
Just as a word of note, while the SMSL iDEA and the Sabaj DA2 seem to be identical in terms of PCB layout and parts usage, the Sabaj analog to the SMSL IQ seems to be slightly different.
This is the Sabaj DA3:
http://www.sabaj.com.cn/productshow.asp?id=74
Not only are the TCXOs used of a different brand, the PCB layout is slightly different. The stated specifications are ever so slightly different as well; the Sabaj has a measured DNR of 125.219 dB, while the SMSL has a measured DNR of 125.559 dB. The Sabaj has a specified power of 56 mW into 32 ohms, while the SMSL, as stated previously has a power of 55 mW. Thus, the stated THD+N for the Sabaj is slightly higher at 0.00038% compared to the SMSL's 0.00033%. Now, these are tiny, tiny differences that ultimately are indiscernible to the human ear, but the differences do suggest a slightly different parts bill. Because the SABRE9018Q2C is an SoC, there's not much tweaking to be done in terms of the sound. Both devices, like the iDEA/DA2 before them, will likely implement a bog-standard symmetric sinc filter. The only differences governing the end result for sound will be determined by how clean the voltage is going into the reference inputs of the SoC, and this factor is governed by PCB layout. I don't know what the real PCB layout of the SABAJ looks like, but from the small snippets,
On a more obvious note, the Sabaj DA3 seems to be thicker, less wide, and less long than the thinner, wider, and longer SMSL IQ. Overall, IMO, the SMSL is a little better looking. The prices are also different: a quick search on Taobao shows the SMSL is more expensive at ¥750.00 (~$114), while the Sabaj is substantially cheaper at ¥ 549.99 (~$84). Keep in mind that the Taobao prices for the Sabaj DA2 (¥ 368, ~$56) are also cheaper than those of the SMSL iDEA (¥ 468, ~$71).