On one hand,
in integrated you can make signal path shorter. Especially in low power SET amplifier. You can build 2A3 or 45 amplifier using only 2 stages or 300B with only 3 stages.
In separates you need more stages and more interconnect cables. Each amplification stage, capacitor and cable add distortions and noise.
On the other hand,
in separated components you can use monoblocks with very short speakers cables, separate power supply transformers and chokes for each channel improves channel separation. A separated power supply for preamp and phono stage make noise level much lower.
in integrated you can make signal path shorter. Especially in low power SET amplifier. You can build 2A3 or 45 amplifier using only 2 stages or 300B with only 3 stages.
In separates you need more stages and more interconnect cables. Each amplification stage, capacitor and cable add distortions and noise.
On the other hand,
in separated components you can use monoblocks with very short speakers cables, separate power supply transformers and chokes for each channel improves channel separation. A separated power supply for preamp and phono stage make noise level much lower.