Pre-amp newbie question


I've recently returned to vinyl after a long hiatus. Please excuse my naiveté on the subject of pre-amps but back in my younger days I couldn't afford such equipment and never really researched it. Now, I constantly have the upgrade bug. My question is: Would I hear a big difference by by-passing my stereo pre-amps phono stage and going with a dedicated phono pre?

I currently have a Rega P3/24 with a Dynavector 10x5. Further down the chain is a Parasound P7 pre-amp and Parasound A21 Amp. The phono stage of the P7 is MM/MC with input impedence of 47k and 100 ohms respectively. With the high output Dynavector the sound is remarkably good but could it be better with a dedicated phono pre-amp?

I'm looking at a Musical Surroundings Phonomena II which has multiple settings for impedence and gain and is compatible with both MM and MC (high and low) carts.

Embarrassingly, the whole subject of ohms, loading and gain confuses the heck out of me so any input would be greatly appreciated.
A few general remarks
generally, once you get up to 1mVolt or more a mm input can be used. Generally again, under 1mVolt it is usually better to use a MC input, due to the higher gain needed.
Most MM phono preamps are preset to 47k as a load, as yours is.
Your dynavector wants something of at least 1k ohm or greater, so the 47k could work. You also have choices of 1,2,50 and 100k to play around with and find out how it sounds to you.
AT 2.5mVolts a gain of 40 should give your around .1 volts which times your preamps gain, 14, should give you about 1.4 volts to your amp. Your amp has an input sensitivity of 1 volt so that should be enough to get you going.
You can then improve the loudness,sound, gain, by increasing the gain to your preference.
The various loading possibilities are there for you to find out what sounds best to your ears. It is always nice to have choices.
Hope that helps. If my numbers are off I am sure someone on here will correct me, thankfully.
Dedicated phono stages are better than built in ones, whether it is worth the money to you is another question. If you go with something like the Project Tube Box 11 SE or the Dynavector P 75 [ I am a dealer for the Dynavector] you will notice a considerable difference; these sell new for around $700 . If I didn't want to spend this much I would get the Blue Circle "Thingee", cheap, no looks, but sounds good. I sold Blue Circle in the past. In my own system I spent twice as much for the phono stage as the line stage but I have a lot of vinyl.
For $795, take a serious look at the Ray Samuels Audio (RSA) F-117 Nighthawk MC/MM phono pre-amp.

I have the Dynavector DV-20X Low MC Cartridge mounted on my VPI Scoutmaster and even though the Dynavector P-75 MK-II was a great match for my Dynavector cart, the F-117 Nighthawk is better (for roughly the same price).

As a bonus, the settings can be changed on the fly via front panel knobs (no need to open up the unit).

I've had mine for roughly 2 weeks now and I've been totally blown away by the F-117. I even had the chance to compare it to the Nagra BPS (3x the price of the F-117) and the F-117 had better, tighter, deeper bass than the Nagra BPS!

RSA F-117 Nighthawk:
One of the many benefits of AudiogoN is buying used equipment to evauluate and re-sell if it the equipment is not satisfying. You should be able to buy a reasonably priced phonomena II on this site. Everyone has opinions and they all.. are subject to their personal experiences. Those experiences may or may not be relevant to you. In your room, with your favorite music, on your system, you are best off trusting what you hear with your ears. Take some time and try different equipment.

"Dedicated phono stages are better than built in ones"

I don't know how you can make an unequivocal statement like that. Also, one has to pay for the replication of a power supply, case, etc., and a built in phono sections can be very good. It depends on the designer. I much prefer the phono board in my BAT pre to the outboard models I've tried (Rogue and Dynavector.)
I agree with Daverz; whether an outboard phono stage is better than what you're using now is something you'll need to determine by listening. For example, I found the Grado phono stage to be better than the built-in stage of my LK1 preamp, but not quite as good as the phono stage in my Audio by Van Alstine OmegaStar PAT-5 (when using a Grado Green cartridge; I did end up buying a Grado PH-1 so I could try Grado's low output cartridges, which my OmegaStar lacks the flexibility to support).

The Dynavector P-75 sounded good, but no better than the built-in stage of a Linn Wakonda I was auditioning at the time (comparison made with 10X5 cartridge), and I didn't like the combination of the 10X5/P-75 as well as the less costly Grado Green/PH-1 set.

I've only heard the Musical Surroundings Phonomena II in a dealer showroom and it impressed me as a good-sounding phono stage with lots of flexibility, but I didn't compare it with anything familiar to me. If at all possible, compare it to what you're using now before making a purchasing decision.
The reason I can say it is because it is true.No preamp can have the space to to contain phono stages like the two I use , one of which weighs 75 pounds by itself and the other 50. The best phono stages are all stand alone ones, the Dynavector is better than the phono stage in my $5000 integrated amp, which was in Stereophile's Class A when it was in production. If you look at ARC, Conrad Johnson, Boulder ,Naim, etc, all their top preamps are line stages without phono stages. The Rogue and Dynavector, while good , are not among the top phono stages. My best phono stage cost over twice as much as my line stage, both originally and when I purchased them used. It is true that you can save money by having a built in phono stage and they can be quite good but the highest level of performance will be from separate stages.
I second the Ray Samuels Audio F-117 Nighthawk phono stage for $795. It's a great little unit and very easy to use and adjust from the rotary front-panel controls. You won't be disappointed...
The OP is still going to have to decide for himself how his current pre-amps phono section compares to whatever he can afford in an outboard unit. Nostrums like "separates are always better" are not practically helpful IMO, though I'm sure they move more gear.
Jrtrent: What is your favorite phono preamp when using a Grado low output cartridge? I use a Grado PH1 with a Grado Signature Sonata 1 and love the sound except for a little background hiss from the PH1.
I never said "separates are always better" but "the best stages are separates" , which is quite different.