Are monoblocks better than stereo, with tube amps?


I am only in the research phase of audiophilia. My present system includes a creaky NAD 150w amp and ghastly sounding speakers from a "rack system" circa 1988 Stalingrad. Anyway, I am hoping to eventually save for a tube set-up with a kind turntable and sweet, costly speakers. I am wondering if there is any advantage to using a monoblock system for amplification and why.
mr_stain
thanks for the responses, which have led me to more questions.
Czbbcl, atmasphere, unsound; what do you mean by 'modulation of power supplies', 'proximity', most importantly, what factor involving amplification's sound is more important then the monoblock versus stereo argument? Also, I understand a bit about why speaker wire should be shorter than interconnects, but should interconects literally be quite long (forgive the obtuse questions)
In simple terms, modulation of power supplies refers to the effect different channels drawing from a shared power supply has. This may not be as big an issue with stereo amps that are "dual mono", or even to a stereo amp that has a very robust power supply. Proximity usually refers to the potential for channel cross-talk amongst other things, such as power draw, heat dissipation, placement ease, etc.. The ultimate sound is the most important factor involving amplification's sound. Seperating the channels is only one aspect of designing an amplifier, and certainly not the most important one, as Atmasphere and Czbbcl have wisely pointed out. As I said, if all else is equal there can be advantages to mono amps, but, in and of itself there are many other important considerations, especially when there are budget considerations. That is why I use a stereo amp, even though, I appreciate the advantages of mono amps. As to the relative lengths of interconnect vis a vis speaker cables, there are differences of opinoion here as well. Decisions as to relative length may be best determined, specificaly to each system (including the specific cables). Personally, I usually prefer to use shorter interconnects and longer speaker cable. There are some other advantages to mono amps as well,that again, in themselves don't necessarily make them superior. I humbly suggest you review the archives. You will find a quite a bit of discussion on mono vs. stereo amps and short/long interconnects vs. short/long speaker cables.
I prefer to run mono amps which allow me to run very short speaker cables with long interconnects. OTOH, I run everything balanced, so I can get away with that.
Like Unsound I also run longer speaker cables and prefer shorter interconnects. I am also a cj fan and that has also been their recommendation concerning their equipment.
The advantage of a rock steady power supply can be exaggerated. Let's say that the music momentarily requires a 40 volt level at the speaker. The amp's power supply is 80 volts nominal. No problem. Now suppose that due to prolonged high rms level signal the power supply "sags" to 70 volts. Can the required 40 volts be delivered? Sure. The transistors just turn on a bit more. In fact, 60 volts, or even 50, might be the nominal power supply voltage for a lower rated version of the amp that is perfectly capable of the 40 volt output.

Some amps are deliberately designed with a high voltage power supply lacking ability to maintain this voltage very long. This enables the amp to follow music signals much better than its continuous rms power rating would suggest.
That "rock steady" power supply is expensive, and so long as your signal is music it may be an unnecessary expense.