# Introducing the QA480 **URL:** \ **Category:** Uncategorized\ **Created:** [July 23, 2020, 5:09pm UTC](https://forum.quantasylum.com/t/introducing-the-qa480/138 "2020-07-23T17:09:18Z")\ **Posts on this page:** 1\ **Showing post:** 7
**Author:** ![matt](https://avatars.discourse-cdn.com/v4/letter/m/a6a055/32.png) [@matt](https://forum.quantasylum.com/u/matt)\ **Post date:** [August 5, 2020, 4:38pm UTC](https://forum.quantasylum.com/t/introducing-the-qa480/138/7 "2020-08-05T16:38:25Z")
That’s a good question. I think for now, in loopback, there probably wouldn’t be much difference now that the errant 2 kHz that was showing up in the notch is gone as that limited the performance. But, once you stick a really high-powered class D DUT in the loop, maybe it would help. Specifically, there are some really high performance class D amps with that are hitting -116 dB THDN and with 131 dB of dynamic range that could conceivably demonstrate the need for additional decoupling. I wrote a short study on the differences between the common high power class D (such as TPA3255) and this next generation class D (Purifi 1ET400A) [HERE](https://forum.quantasylum.com/t/measuring-amp-noise-with-the-qa451-and-qa401/142). The study looks at noise floor. If there was a situation that might demonstrate the need for more isolation, it’d be that. That amp runs at a 500 kHz switching frequency, so the ~90 dB of attenuation the QA451 has at 500 kHz would help. But I don’t know if it would be enough. The plot below is the SPICE sim of the QA452 filter (from [HERE](https://quantasylum.com/blogs/news/introducing-the-qa451)). ![image](https://canada1.discourse-cdn.com/flex032/uploads/quantasylum/original/1X/ade8c926af5d6d7b7bc5f07de149101a2aa4a790.jpeg) --- _[View the full topic](https://forum.quantasylum.com/t/introducing-the-qa480/138)._