I feel like Softube wins here quite easily followed by Red Rock. The low end when being boosted is warm + tight., though not reaching the original from what I can tell by seeing hardware videos. The original is even warmer, rounder, tighter, aswell delivering beautiful air to upper mids and top end. It can also be cranked up while still sounding "clean".
Here is an example, delivering quite a good idea how the actual hardware sounds:
In this longer quiet fun to watch yet serious video two original hardware pultecs, a hardware clone from Klark and the Waves emulation are being compared, while being well described in their use for the demoed situations.
Btw the Waves´ Puigtec-EQ is currently on offer for 30$:
Still, compared to other software emulations (including Waves + several VST) I find Softube´s version the best one from what I´ve heard so far.
Then at least compared to Red Rock, Softube is a lot more expensive, especially if you take intro and current sale price into account.
Sure there is aswell the compressor, then at least for the price of 499 Euros or 166 Euros if you divide by the number of included devices, I wasn´t justifyingly impressed though it is still quite a good sounding software compressor.
Saying the price gap is unevenly bigger compared to the quality gap I find.
If you are looking for the best (?) sounding software emulation to have or potentially need it professionally and got the money to spend, one might consider going for Softube´s device, though I would still feel it´s simply a bit expensive for what it is in comparison to what we got as RE alternatives in Red Rock.
For that price I would prefer going for a hardware clone anyway. The Klark clone is at around 229 Euros for example (even though it´s merely one device out of three).
Now, regarding the sound itself again, you can hear the difference between Softube´s and Red Rock´s Pultec in the already mentioned low end where Softube is simply tighter and also punchier when boosting the bass. Red Rock´s lowend is less defined, aswell introducing a sort of rumbling at already around 3dB lower settings compared to the point Softube´s EQ starts to distort at (with a more pleasant tone I find).
In that sense just mind the original of the first video still sounding clean, when being cranked up on the synth line.
I also find Softube´s RE opening up mids + highs in a more pleasant way compared to Red Rock´s version that is struggling a bit in that regard, as in relation to the top end it does not get the upper mids to sound as balancedly boosted. I aswell find the grittiness of mids + highs being smoother on Softube´s device.
After all, I feel Softube and Redrock are the only two RE approaching onto the path towards the original hardware unit.
Kuassa and Blamsoft may use the basic technical Pultec principle yet at least here their versions present themselves quite differently, like I basically could barely (if at all) find the original in them soundwise.
I notice Kuassa´s take sounding pretty screamingly screachy in the mids/highs while the low end sounds a lot less impressive (if at all
) compared to Softube´s or Red Rock´s warm lowend boost, let alone the original hardware. Already Red Rock´s EQ is much smoother + warmer in that regard.
Blamsoft I just briefly tested while comparing instensively especially Softube´s and Red Rock´s RE along watching Pultec videos, because similar to Kuassa´s version it sounds different in it´s sonic approach/emphasis and even less to my likings in terms of distortion.
Coming to the conclusion, if you like having an affordable Pultec-style emulation in RE format and also similar to or at least in the direction of the original, I very much recommend Red Rocks devices even though they stand behind in some aspects compared to Softube´s Version.