If you have a parallel effect loop, you are correct to use killdry – that is what it is for.

But, you cannot have multiple chained effects. To understand this, think about what is happening: the first unit in the chain gets a dry signal at its input, and then its output is just the wet signal. With just one unit, this would be mixed with the loop dry signal, and all would be as it should.

But, if you then put another unit in series, this only gets the wet signal (which could be a very low level, depending on the first mix level), so this will not do what you want. Etc, etc.

There is no real solution – a parallel effects loop really only works for one effect, unless you feed them all together, and have a mixer to mix all the wet signals – too difficult.

You could try setting killdry OFF on all but the last unit in the chain, and then setting killdry ON for the last one. There may still be too much dry, but with adjustment of mix levels you may get a reasonable sound.