Considering the budget basically the only choices are consumer multichannel PCIE soundcards.
Creative AE-5 (ES9016) and AE-7 (ES9018) uses single-chip multichannel DACs, as well as Asus Strix Raid Pro (ES9006) and DLX(ES9016).
AE-9 uses a non-pro ES9038 as stereo output and ES9006 for other channels and it is out of your €250 budget. Also, the design is pretty silly. If they use a breakout box, they should put all analog circuitry in the breakout box rather than putting them on the PCIE card. The PCIE card should only have digital I/O and DSP/controller chips, not analog RCA jacks, opamps and DAC chips.
Reviews:
https://www.ixbt.com/multimedia/asus-strix.shtml
https://reference-audio-analyzer.pro/en/report/dac/creative-sound-blaster-ae-5.php
https://reference-audio-analyzer.pro/en/report/dac/asus-strix-raid-pro.php
https://reference-audio-analyzer.pro/en/report/dac/asus-strix-raid-dlx.php
The measurements look decent but what made me worry is some of the cards like AE-5, AE-7 and Strix Raid Pro are not using premium ADCs so analog loopback test are rather meaningless. Furthermore, Stirx Raid DLX in the reviews has a non-flat and leaky digital filter with about 3dB attenuation at 20kHz and a lot of imaging above Nyquist. On the other hand, the cheaper Strix Raid Pro uses a standard sharp filter. Don't know if the digital filters are configurable in the driver or not.
Also, RCA jacks on the PCIE card itself is a bad design. PCIE 1x card only has very few pins and the contact area with the slot is small and pretty insecure. Inserting and removing the RCA plugs can cause trouble and make the card unrecognizable, requiring users to open the case and reinsert the card. I can say this as a user of the X-Fi Titanium HD which also has RCA jacks.