No matter how well a filter is put together; they all have a sound. This becomes clear pretty quickly when we put it next to the Isotek Aquarius EVO V. This one costs about 2,500 euros, which of course makes it 1,000 euros cheaper than the Pura Sauropoda. Nevertheless, it is interesting to put them side by side, since many people are familiar with the Isotek products.
A common “complaint” from users trying a filter is that there is a loss of speed. The “kick” and “attack” is gone. This is possible, but only when you have applied a filter that is inadequate. This is a particularly audible problem on power amplifiers, since they can load very dynamically and then often require a lot of current (amps). A filter that cannot deliver enough energy will result in a flat, dull and sometimes glassy sound. A good filter will often result in an increase in blackness and calmness.
At Alpha Audio we have been using the Isotek Titan in the main system for years. First the EVO3 and now the V5. Recently we also have a YETI reference at the editorial office. This to be able to mix and match better. The Isotek has a completely different construction than the YETI. Both are galvanic decouplers and both are balanced – which is very nice – but both also address it differently, which is interesting. But we digress.
The reason we briefly touched on this example is that both the YETI and the Isotek can deliver a lot of current. In fact, the Isotek is explicitly a High Current filter. It is designed for power amplifiers. YETI doesn’t specify it as such, but the Pass can play fine on it without us feeling like things are being pinched off. That wasn’t the case with the Bryston either.
The Sauropoda is not for power amplifiers, but for sources. That’s why we especially connected the Sonnet Pasithea to it. The Pasithea has an insanely low noise floor as well as extremely high resolution. So this one should be able to make you hear what’s going on perfectly.
Calmness and space
What is immediately noticeable is that it pays to check the polarity. At first, the polarity was incorrect, resulting in a much flatter image. After some checks with the Kemp Ultimate Polarity Checker – cool device! – we got everything right and immediately heard a substantial difference especially in imaging. Conclusion: a balanced design definitely has advantages for devices connected to it, but you still have to connect the filter properly. But hey: we are used to that in this hobby, right?
The Sonnet, as we predicted, lets you hear these things flawlessly. And with the whole system playing nicely again, we can also hear a clear difference between the Pura Sauropoda and the Isotek Aquarius. The Aquarius has a slightly fresher sound than the Pura Sauropoda. The latter brings a little more glow and “chest” to the reproduction. The midrange is a bit richer in sound. What fits better is of course up to you: above all, it must fit within your system.
Both filters bring a pleasant enlargement of the stereo image compared to directly into the wall. The way they do it, however, is different. The Sauropoda brings just a little more “acoustics” than the Isotek. We feel a little more present with the recording. The Isotek is just a little drier and a little more clinical than the Pura. This difference comes with the price. Because again: for the Pura you spend 1000 euros more than the Isotek.
In terms of speed, we can be brief: we did not hear any slowdown. The Sonnet would no doubt let us notice the slowdown. We have not noticed anything.