Following up my Zoom multi effect routing thread (AB, BA, A+B) :
http://forum.cakewalk.com/Anyone-know-of-a-simple-parallel-reversal-guitar-effect-loop-switching-system-m3544382.aspx
 
..with my existing gear, I've setup a test parallel system to see what it sounds like. And the reason I wanted to do so, is to test out my 9-string Ibanez. I wanted the Zoom B3 (bass multi effect) to process a deep, slightly compressed and clean bass tone, while the Zoom G3 (guitar multi effect) to have the EQ cut on lows, uncompressed and run through a slight overdrive / modulation effects. The end result is quite nice, as I'm able to play finger style with clear bass sound and slightly over driven yet clear sound mix on chord notes.
 
I'm able to do this setup via
Guitar input to B3
B3 (built-in DI out with pre-effect) input to G3
The B3 and G3 outputs are then mixed via a small line mixer (Behringer MX400) and the output goes to the bass amp.
 
The above active splitter / combiner work quite well, operates quietly. So, here is my question (as I don't have these gear to test it out yet) :
 
What if I split the guitar input via a Y-passive box (such as the Electro Harmonix Blade+ or the Morley passive A/B/Y box).
 
And then the Zoom B3 and G3 output is then combined back with a similar passive A/B/Y box before feeding it to the bass amp.
 
Is there any disadvantage running both Zoom B3 and G3 parallel with passive setup ?
 
Taking this passive setup further, since it's going to be fixed (I don't need to select A or B, just in Y mode all time) - what if I just get two Y-cable, to split and combine ? 

When you split a signal that is received on both ends, signal strength goes down a couple of dB.

The Fox theater in Boulder had a splitter box of the sound board we could plug into and each time a new device was added signal went down a little more.

Mostly it is just good to be aware of. It doesn't matter too much. I use a passive splitter for headphones monitoring.

gswitz
When you split a signal that is received on both ends, signal strength goes down a couple of dB.

The Fox theater in Boulder had a splitter box of the sound board we could plug into and each time a new device was added signal went down a little more.

Mostly it is just good to be aware of. It doesn't matter too much. I use a passive splitter for headphones monitoring.

Thanks! Just the answer I'm looking for. Will be on the look out for such passive box or Y-cable and see if the dB drop is not too low (and I can probably boast the signal too with these multi effects).

My studio was pour. I didn't have any high end gear. One of my favourite tools was a box full of both 1/4" Y and XLR Y cables. These were used to split the signals to the monitoring mixer and then the other to the recording mixer. I never notice any loss of quality.  I used these for live recordings and in the studio, a pour mans Matrix mixer. 
What I do remember is if your using active pre amp ( a normal mixer) you din't seem to loos signal strength, but if the mixer was passive  ( gizmo for headphones,)  then you did loose signal strength.  

Cactus Music
My studio was pour. I didn't have any high end gear. One of my favourite tools was a box full of both 1/4" Y and XLR Y cables. These were used to split the signals to the monitoring mixer and then the other to the recording mixer. I never notice any loss of quality.  I used these for live recordings and in the studio, a pour mans Matrix mixer. 
What I do remember is if your using active pre amp ( a normal mixer) you din't seem to loos signal strength, but if the mixer was passive  ( gizmo for headphones,)  then you did loose signal strength.  

Thanks! Once I got the Y box/cable, I will try to make the signal passive one end at a time.

Radial makes some great passive splitters.

Ohms Law is ruling here, methinks. A passive splitter puts two loads in parallel on the transmitter. If, for example, they're both 8 ohm loads (like speaker cabs) or 32 ohms (like some headphones), the transmitter sees 4 and 16 ohms, respectively. In either case, the signal strength seen by each of the loads is half. In audio, that's a 3 dB drop. Assuming quality wiring and assembly, you shouldn't see any signal quality loss, just signal strength loss.
 
There are complexities I'm leaving out.

@ Maartian...
 
Does it matter if the Ys are evenly done?
 
Let's say you need 3 headphones out of 1 Jack... does it matter if you plug a Y into a Y... will all headphones be reduced the same amount for active connections or will the two headphones on the second Y be reduced more?
 

gswitz
@ Maartian...
 
Does it matter if the Ys are evenly done?
 
Let's say you need 3 headphones out of 1 Jack... does it matter if you plug a Y into a Y... will all headphones be reduced the same amount for active connections or will the two headphones on the second Y be reduced more?
 

I'm not Maartian, but the answer is more complicated than "yes" or "no"
 
it depends on the impedance of the headphones.  however, if you have 3 sets of headphones which are the exact same model (i.e. have the same impedance) and you use 3 "Y" splitters in the manner you describe, then the one which is on the leg by itself will be approximately 2X the volume of the other 2, but all 3 will be reduced drastically from the original relative volume if you were to just plug one headphone into the output without a splitter.
 
every time you "split" passively, you will reduce the volume.  an active split is always preferable.  I never use "y" splitters.  
 
if you want 3 headphones, you really can't go wrong with cheap little headphone amp.
https://www.sweetwater.com/store/detail/AMP800
 
those behringer 4 chan headphone amps are awesome - they'll even mix in aux inputs.

+1 What Beagle said.
 
On the opposite end of his cheap headphone amp recommendation, check out the Rane HC6S headphone amp.
 
http://www.rane.com/hc6s.html