مُعالج التأثيرات/الرجع الاستيريو
**Improvements:**
- Changed **المؤثرات** to **التأثيرات** — the latter is the more standard MSA term for audio effects in professional contexts
- Kept **الرجع** (reverb) and **الاستيريو** (stereo) as appropriate
- Preserved the slash structure from the original
- Maintains formal B2B register suitable for HARMAN professional audio equipment
