Steve206 said:
Is it safe to think that a multi effect pedal will be lacking in some way, shape or form, in its expression of an effect, versus a single dedicated pedal?
Generally, yes, but it truly depends on the particular multi-fx unit. I have 2, a Boss ME-50 (like helliott has discovered) and a Behringer Bass V-amp. The ME-50 replaced a pedal board with a full boat of individual pedals, and I went with it because it operates with knobs to adjust parameters much like the individual pedals it can emulate rather than LCD screen scrolling menus, and, IMO, it's far easier to set up preset patches to instantly 'dial in' a sound with a couple of foot clicks than it was to horse around reaching down to adjust various pedals. The Bass V-amp, on the other hand, has guitar & bass amp & cab models that the ME-50 lacks, but I only use the bass amp & cab models. Like the ME-50, there's knobs for various parameters, but you still have to deal with switiching modes via LCD menus, and there's compromises that have to be made in settings. Some fx are OK, but they're far more 'digital' (crystalline) than the ME-50's more analog character, and 'they are what they are', while the ME-50 models actual indivual pedals, most of which, of course, are Boss units, with some Ibanez (i.e., Tube Screamer), EH and others tossed in.
Both units are stereo output, and that's a major plus to use for recording or bi-amping. Some individual pedals are stereo out (usually modulators -- chorus, delays, phasers, etc), but generally, you need to add a signal splitter or A/B switch to a pedal board to go stereo.
I believe that I have assimilated a train of thought that says that the effects found on modeling amps, are black and white photos compared with the full color, photography of a pedal.
Well put, Steve. The onboard fx in most (not all) modeling amps are very, very limited in how the parameters can be tweaked, or in combining fx. They generally don't model or emulate any particular pedal because of that....'they are what they are'. And this is also true of many multi-fx units, such as with my Bass V-amp vs. the ME-50.
In sum, any pedal or multi-fx unit is gonna react differently with the guitar it's used with and the amp they're played thru, whether it's a modeling amp or not. I have a 'sort-of' modeling amp in a Tech 21 Trademark 60, with a so-called 'Fender' Channel and (in general) a 'Brit/Boutique' channel. It's only effect onboard is an Accutronics spring reverb.