Serum

Many good things in here. Features (the oscillator section, the unison, the wavetable features, the noise and sample loading section, the crazy amount of filters), GUI (visual representation and animation for nearly everything) and sound (clean oscillators, oversampling) are very good.

I didn't like the stock presets as much, but there are third party patches (like Ayin Zahev, Simon Stockhausen, etc.) that really show the quality of this synth. I'm loving the function and sound of this synth.

However, I find the CPU usage way too high, and quickly becomes unusable for me (and I have a pretty powerful system i7 4790K at 4.4 GHz, 16 GB DDR3 2400 RAM, Samsung 850 Pro SSDs, an RME Babyface audio interface, an optimized for audio Windows 8.1 OS, etc..). I always end up using DUNE 2 instead in a production. But for messing around with the synth alone, Serum is good.

I made a little, quick and easy test on FL Studio:

1. A 7 voice unison (density in DUNE 2) saw wave, 16 polyphony, longest amp envelope release possible and filter activated on Serum drove my system close to 30 to 35% CPU load with all voices playing, and if I mess with the detune knob, ugly spikes drive it to 50-60%;

2. Meanwhile DUNE 2 is 3-4% CPU load and it stays stable no matter what. Even if I bump up the DUNE 2 unison voices to 8 (that is, 8 copies or layers of the same sound playing at the same time), I still can't reach the 30% Serum demands for its single layer.

3. Sylenth1...6-7% CPU load... (this is a surprise to me, DUNE 2 even outperforms Sylenth1, the gold standard in sound/cpu usage ratio..).

4. Spire...15-20% CPU load.. (this one is also considered a CPU hog, not as bad as Serum, though)

EDIT: I did the test again, with same settings on all synths. As suggested by Steve Duda himself, the settings are: Long sustained notes in the piano roll (FL Studio), no release at all, 16x polyphony, 16 notes playing at the same time, filter enabled. The results are:

1. Serum: 34%
2. DUNE 2: 3%
3. Sylenth1: 6%
4. Spire: 6-7%

Not super scientific tests by any means, and certainly not indicative of a real world performance for everybody, but it could give a very rough idea of the CPU load situation (as of the time of this little test, with Serum version 1.04b3).

IMHO, Serum seems like an unfinished product and it needs optimization. If you want to buy this synth, make sure you have the CPU power to back it up.

But it is one fine sounding synth (not better or worse than DUNE 2 or Sylenth1 in this respect, just different) and it deserves better. I guess those fancy animations come at a price [:?].

It has a great potential to be one of the greatest.

[comment from Steve Duda]: DUNE is multicore and you're not looking at the activity across your cores so it could be up to 8x what you're reporting. Sylenth caps at 32 polyphony, if you allow Sylenth to play 256 voices it's consumption is about 3x what you report, at least here. I don't trust your tests. Serum takes more CPU than the others (and for good reason, there is a measurable difference in oscillator quality compared to some of your test comparisons) and runs single-core, which can be prohibitive if you need 256 voices from a single instance but that isn't really a real-world example. There's users that have used up to 90+ Serum instances in a single project, as hosts should be spreading things to various cores which is in most cases the optimal way of operating, rather than a single instance spreading it's workload across the cores (as there is overhead doing such a thing).