I've been using a Rogue 99 Magnum with a DNA225 with great results. Used would be right in your price range...
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First what have you been using before?
In my knowlege there aren't too many tube preamps that are realy good for DNA500 which dictates the limited choice.
Manley Shrimp seems to be a great match only if $1k is true for used.
Not sure if this one will outperform your current setup if that is what you're aiming for with tubes.
I also need 2 pairs of preamp outs.
Keep in mind that most (though not all) preamps with two sets of output jacks simply jumper them together, at the connectors, just inside of the rear panel. A relatively small number of preamps provide separate buffer stages for the two outputs.
That has two implications if you choose a preamp that does not have separate buffer stages for the two outputs:
1)The preamp will see a load impedance that represents the parallel combination of the input impedances of the two devices to which it is connected. The specifications for the DNA-500 indicate that its input impedance is 10K ohms. If the preamp were simultaneously connected to another 10K load, the combined load would be 5K, and you would want to have a preamp with an output impedance of no more than 400 ohms, to maintain the ratio Steve recommended of preamp output impedance to power amp input impedance.
If the input impedances of the two loads are not equal to each other, they combine as the reciprocal of the sum of the reciprocals of the individual impedances. If there are exactly two loads present, that is the same as the product of the two values divided by their sum. So 10K in parallel with 25K, for example, would yield a combined impedance of about 7.14K, which would mean that the maximum preamp output impedance that would be consistent with Steve's recommendation would be 800*(7.14/10) = 571 ohms.
2)You could use a y-adapter cable in conjunction with a preamp that just has one set of outputs, and (assuming the cable is good quality, and connections are good), the results (and the required preamp output impedance) would be no different than using a preamp with two sets of outputs which are not separately buffered.
Keep in mind, also, that running two sets of cables from the same preamp output buffer stage (whether via a y-adapter or from two sets of jacks that are connected together within the preamp) will double the cable capacitance that the preamp has to drive. If cable capacitance is too high in relation to the preamp output impedance, upper treble rolloff will result.
Marakentz's suggestion of the Manley Shrimp seems to be a solid recommendation. It has the specs to drive the 10Kohm input impedance of the DNA-500 without bass roll-off (because of its 50kohm output impedance), and it has two sets of outputs.
Also, you might keep an eye out for a used Juicy Music Peach I. That preamp has a LoZ switchable output impedance, and has the sonic characteristics your described. However, it only has one set of preamp outputs.
Do you need two sets of preamp outputs, or can you use a set of line level tape monitor outputs?
You can run a sub (or subs) without a second set of pre outs by using these ACI Speaker Level Converters (scroll down the page).
They connect at your amplifier's speaker outputs and into your subs' rca line level inputs via RCA interconnects. I've used them , and they work great, IMO.
08-14-09: TvadTypo. 50kohm should be 50ohm.
Not quite your amp but I have a DNA-1 with McCormack Platinum mods. I use a Art Audio Gill Alana tube pre with success on a variety of speakers. My Rogers 15 Ohm LS 3/5a's, Harbeths 7 es3's, Meadowlark Blue Heron II's, Merlin VSM-Mmx, and B&W 801F's were thrown in the system All but the Harbeths seem to shine with this Alana: clean, full soundstage with very good definition and clarity. The Harbeth's sounded somewhat muddled, just didn't seem to like the combo. An Art Audio preamp shows up on 'Gon from time to time; I would not hesitate to mate one with the 500 if it is in your price range.
have very good results driving McCormack with a Golden Tube SEP2. The SEP3 is the same pre but with a separately boxed power supply (for allegedly lower noise). Great stage & imaging, full bodied, musical, warm sonic signature, remote control, very low noise (much unlike many other tube pre's that I tried, some quite expensive). The SEP's are out of production but can still be found inexpensively, although unfortunately Solo Electronics is history. Service is yet available from a number of sources if ever needed. The single ended triodes are readily rollable with a number of alternatives, but I have never felt the need. Very satisfied with this pre; bigtime performance for low cost.
IMO, the output of the Cary preamps is much too high to match well to the DNA-500's 10kohm input impedance. Rolled off base and/or highs would be the likely result.
John Atkinson writes in his Measurements section of the Feb. 2004 Stereophile review of the SLP-98, "...but [the output impedance] rose at 20Hz to 6.8k ohms, due to the limited size of the output coupling capacitors. This will prematurely and audibly roll off the bass with power amplifiers having an input impedance of much less than 20k ohms."
10kohms is even too low for the Lamm LL2 Deluxe, IMO, and the LL2 Deluxe is *right* in the wheelhouse of what Foster_9 describes as his desired sound and output configuration.
Just get a used Juicy Music Peach, set it to Low output impedance setting and you are done.
I have had both a Manley Shrimp and a Peach hooked up to a Gamut D200 solid state amp with a relatively low input impedance and the Peach won hands down. The Shrimp was lacking soul in comparison. It sounded nice and checked all the typical audiophile boxes but it just didn't have the flow and naturalness of the Peach.
Sold the Shrimp a long time ago. Still have the Peach.
I made this suggestion earlier, and I agree. Foster_9 has said he needs two preamp outputs, but if he uses the ACI Speaker Level Converters to run his subs, he can use the Peach I and have everything he wants (plus save half his budget if he buys one used).
Thanks again for all the recommendations. Which of the above preamps leans more in the direction of a smooth tube sound as opposed to leaning more to a smooth solid state sound?
Example: I've read that the Modwright Swl 9.0 sounds very good with the DNA-50. But, I've also read that if you're looking for any tube presence with the Modwright look elsewhere, but if you're looking for neutrality the Modwright delivers.
Juicy Music Peach I and VAC for sure have the smooth tube sound versus the more solid state sound of Modwright (IMO).
The VAC Standard LE would be the preamp in your price range. With a 350 ohm nominal output impedance, it could be OK with the DNA500.
I'm not sure the output impedance of Fplanner's Phi 2.0 preamp. Perhaps Flpanner2000 has some output impedance measurements.
If you can find a used VAC Standard LE, it might be worth a try. They hold their resale value. I'm not sure if the Standard has two sets of preamp outputs, though.
It was also much better than "OK".... you should be very pleased if that's the route you choose.
What I meant by "OK" was that it will work OK, not that it will sound only "OK". If the bass is extended and controlled, it will sound exceptional.
The 350 ohm output impedance was a little concerning considering output impedance can often go much higher than the nominal figure, but perhaps the VAC Standard LE is similar to the VAC Renaissance Signature Mk.II preamplifier tested by Stereophile, which has a 150 ohm output impedance that doesn't vary significantly from that figure.
If Fplanner2000 says it sounds good with the DNA-500, then it's a very safe buy-and-try component and a good recommendation.
Fplanner2000, how many preamp outputs does the VAC Standard LE have?
I have also had a Vac Std. LE on loan for a week from a friend. Great pre but a lot more tube rush in my system than the Peach.
Maybe my friend's tubes needed replacing so I'm not sure that is a fair statement. It sounded great, however.
Also owned the Modwright for awhile. It was very quiet and had great prat. Too solid state sounding for my taste, however.
I'd take the Peach any day of the week over the Modwright.
In fairness, though, the Modwright I owned was an earlier unit that did not have tube rectification. From what i have read, this makes a very nice difference and may make it a closer race with the Peach.
Hope my audiophilia nervosa helps you with your search.