The outputs of these two stages were then summed via a simple R-C network back into one channel. The theory behind this design was that any distortions created at the transistor junction of the NPN topology would be inverted PNP topology and therefore cancelled at the summing point. Interresting design approach and one that was improved upon in two subsequent models, the Integra P-304, P-306, P-308, and P-388F with the P-388F being the last model to use only discrete transistors in its design. Subsequent models used integrated circuits instead of descrete devices.
Its shortcoming was that it only selected two high-level inputs, a tape loop, and MC or MM phono cartridge (yes, it did have a similar circuit topology for the additional gain stage of the MC pre-preamp).
No one else ventured into this intense esoteric realm and after a few years the design faded into audio obscuredom...until 2013. Onkyo revived this fundamental design, improving it again, and resurrected it as the P-3000R.
Now the P-3000R does not feature the Mu-metal shielding of its predecessors, does not have the beautiful rosewood cabinet, and it does not provide a well-designed moving coil pre-preamp, but it does retain the dual-mono NPN-PNP circuit topology and incorporate a few modern updates like a torroidal transformer, remote control, and alphanumeric display. Its limiting factor is that it is still a mostly single-ended design like its famous P-303 predecessor (it has one balanced input but no balanced outputs). BTW, Onkyo coinded the abbreviation DIDRC (short for Dynamic Intermodulation Distortion Reduction Circuitry) in 2013 to describe its unique NPN-PNP topology and its contribution to the improvement of solid-state reproduction of sound.
I owned a P-303 back in its hayday and found it to be every bit of what it was touted to be. But as time marched on, the unit and I parted ways not by choice but by circumstances. Needless to say that when I learned of this circuit topology being reintroduced I was anxious to hear its improvements.
This unit now selects from three high-level inputs, a tape in/out loop, two optical inputs, two coaxial digital inputs, a USB input, an AES/EBU balanced input, plus the phono stage making it a really nice addition for people with a lot of gear to manage. With built-in 32/192 Burr-Brown DACS, it is a real steal for its price.
After only four hours of play time, this unit settled in and sounded wonderful. As I recalled, the phono section was stellar being so low in noise that I could have been convinced that they still used the Mu-metal shielding. High-level inputs were also dead quiet making this unit non-contributor to any hum or noise that your system may have. However, know that when the unit is turned off, the preamp chassis itself is not grounded to the power cord and can therefore cause a bit of hum to the amplfiier (that is, if you leve it powered on all the time as I do).
After about another 100 hours of play time, the sound again smoothed out even more and transparent is the best word I can use to describe its change. The NPN-PNP topology is carried over to two discrete output stages meaning that unlike many high-end manufacturers who use the same discrete channel to drive two amplifiers from their two output jacks, the interaction between varying amplifier input impedances and the preamp's ability to trive them uniformly is completely resolved by using these two separate stereo driver stages. Individual output level controls allows you to make minor adjustments to the gain differences between amplifiers providing a master-volume level that properly drives both amplifiers. An optical digital output is also offered providing selectable 32, 44.1, 48, 88.2, and 96KHz sampling rates.
This peamp also features a discrete headphone amplifier using this same NPN-PNP circuit topology. A separate volume control is also provided for the headphones and an auto-mute function is applied to the amplifier outputs when headphones are connected (a nice feature). The separate colume control allows you to listen to your headphones at whatever level you desire and then when you unplug them the amplifiers do not overpower you or blow out your speakers.
With my OPPO BDP-105 is connected to the CD input, I put in the C-Major Blu-ray version of Mozarts's Magic Flute. This is an amazing 2013 production comperable to that of a first-class Cirque du Soliel feature. The sets were poised on a floating, rotating stage with towering bridges and pyrotechnics. The orchestra was superbly recorded as were the voices although I personally prefer more emphasis on the percussion section. Voices were absolutely fluid pulling you into the characters even moreso than any other transistor preamplifier I have ever heard. This preamp used in the "direct" mode is strikingly neutral. Adding the tone controls does color the sound just a tad so I prefer listening to it with the tone controls bypassed from direct mode.
The bass was deep and dynamic again with a balanced and neutral signature. Crescendos and pyrotechnic bursts routinely resounded in my listening room providing realism and depth that sucked me into the storyline of human nature without noticing that the sound is what was making the performance so enjoyable.
A switch to another Blu-ray (Pacific Rim) smoothed out the glariness I observed while listening to the OPPO directly driving the amplifier. Even my old trusty Dared MC-7P preamplifier was not able to do what this preamp does despite its fine complement of NOS Mullard tubes.
The phono stage is connected through my pre-pramp (a hand-built solid state design based on this same NPN-PNP circuit topology but a true dual-mono, dual- toroidal supply design). IMHO, this is the best part of the P-3000R for it has the ability to lower the noise floor of analog vinyl to a level you may find hard to believe. Even recordings that I would consider not as good as my reference few sounded more accurate and more revealing than ever before. But with a really fine pressing, such as the cirect-to-disc M&K RealTime Records #RT-101 For Duke, Scott Hamilton breathing into the reeds of his sax was just as I recalled it while sitting in the first row center at the old historic Paramount Theater in Denver. Back in the early 1980s, I had season tickets to the Dick Gibson Jazz Concert series and Scott was one of Dick's routine favorites on the billing. His uncanny smoothness and flawless execution made a permanent impression of how a sax should be played forever in my audio memory. I feel like I am there again listening to this piece although in a much smaller hall.
In closing, the DIDRC topology allows you to hear things that other designs do not, something to remember when auditioning gear. It has a very different sound that to some at first may seem unnatural. What you percieve is not this preamp's unnaturalness but how almost all other solid state preamps color the sound. Once you setle into this difference, you begin to hear its other striking qualities and effortless dynamics.
Although lacking the midrange warmth of fine tubes, this preamp is definitely not sterile or metallic as most solid state preamps are. It is sort of a jump between what the best solid-state preamps do well and what the best tube preamps do well. Overall, I would still prefer lsitening to a well-tubed Audio Research but the differences on all but the best high-end systems are not that dramatic and for most these differences will not be worth the additional cost.
This is a really sweet preamp that does a lot of things spot-on right. First, it is dead quiet (a must) and second it is extremely neutral (also a must once you climb that high-end ladder). Using this unit in your rig will most likley give it some life that you did not realize you had. If you are considering a best-bang-for-the-buck piece of high-end gear, seriously consider buying this.
Is this the best solid-state preamp made? No. Is it a seriously good solid-state preamp? Without a doubt. and one that you will be proud to own. Even if you are the type of person who loves to modify gear, this one will respond really well to tweaks like capacitor rolling.