The always reappearing Cycles noise question:(

Dear Everybody!

Sorry for my lame question as I know there are a lot of threads about the questions of noise in Cycles, but simply could not solve my problem after tried every solution what I red from you.

I’m a little bit new and noob Blender + Cycles user (who tried in the past lot of times Blender with Luxrender, 3D Studio + V-Ray, etc…) and as this is just my hobby there are some|more ‘black holes’ in my practices.

Now have a little project just for my own, as I need to renew my flat and in this case I tried to make some renders for it before the real works.

Some month ago I started it in just some hours and got a very usable result what you can see on the first toilette attachment.

Then some weeks later I tried to continue the project I extend it and made some more complex content, polish etc., and at the and I simply realized that the quality of the renders just dropped down and simply don’t know that from where and how? In the time of my process I saw the problem but did not had a time to search for the reason of it but now as the main works are done I would like to correct the quality and simply could not do it.

Could anybody help me that hat would be the magic to get back the original render quality from the current set-up?

I attached one fresh bathroom render with lot of noise. I also attached a fresh render of a toilette with also a lot of noise. And also attached a render of the toilette without such noise from the past, what was my reference for quality and what I lost and don’t know how?!.

You can check the project file (.blend) for testing bellow:

(The different rooms are on different layers.)

Thanks for your help in advance.

(I tried almost everything but simply could not solve the noise what was not available on my earlier work:(

Tried to change the lights, also the materials, render settings, etc, without success. The current toilette render has a lot more noise with 10k samples as the earlier with 5k samples.)