I think the problem with the Graham Slees is that they are just too quiet. Too quiet in the sense that there is no buzz on them. Too quiet in terms of public awareness of the brand. Too quiet in the sense that “when was the last time you heard someone mention a Graham Slee amp?” Even the enclosure design is very understated. And while the purists may give a nod to Graham Slee’s business philosophy that a great product will speak for itself, in a very crowded market like what we have these days, that simply is not enough. If you imagine a typical meet situation where you have say a table with the Burson amps, another table with WooAudio amps, and another with the Schiit amps, and finally the Graham Slee table. You and I know precisely where people will be queuing up for an audition, and that’s exactly what I’m talking about.
I’ve had a listen to the Graham Slees during local headphone meets, and my impression was just that they are smooth and warm sounding amps and just that. After all it’s a meet condition, and it’s hard to listen to subtle refinements on meet conditions. But listening at home in a quieter setting and with gears that I’m very familiar with, it becomes clear that the Graham Slee amps, especially the Solo SRG II and the Ultra Linear models are a higher resolving amp than the Schiit stuff are.
As the Zana Deux amp has been sold, I find the Graham Slee amps actually doing a very good job of making me not miss the Zana. It has the same smooth tube tonality, and whilst the soundstage is not a good as the Zana, I enjoy the clean and less grainy sound that I hear from the Graham Slee — something that I can’t seem to get with the Zana. Having a grainless sound does boost the perception of clarity and on some music I do feel that the Graham Slee to give a clearer sound than the Zana does. Paired with a high end DAC like the Audio-Gd Ref7.1 and the Bryston BDA-1, I really think that the sound quality is first class and easily the best set up I’ve listened to. Obviously the $2,000 DACs have a lot of role in this, but my point is that the amplifier is very good and scales up very well to a high end DAC to make for a pretty high end system.
So here we are with the three desktop amplifiers from Graham Slee: the Novo, Solo SRG II and Solo Ultra Linear. Special thanks to Rudi, Adit, and Alvon for the loaners.
The Graham Slee Novo
The Novo is the lowest end model in this comparison and can be bought for £212.75 (~$348). It gives a taste of the basic Graham Slee sound of a smooth and warm sound with good clarity. The smoothness doesn’t get in the way in the impression of clarity and is an all around good amp.
Compared to the Schiit Asgard which is priced lower at $250, tonality is roughly in the same ballpark except that the Graham Slee Novo has a fuller mids but a less spacious soundstage. Micro details are also better in the Asgard as they are less obvious on the Graham Slee. The Novo however has a blacker background and is less grainy than the Asgard. The Novo has more upper-mid bass body where the Asgard has more mid-lower bass. It becomes more of a choice of sound signature then, and the Novo will be a better amp for vocal lovers where the Asgard has a more all rounder sound.
Despite the small case and the understated looks, the Novo is actually a very solid performer and it’s quite hard to pick on where the fault is. Overall a very smooth sound, a very clean and black background, very clean separation, smooth treble, good round bass punch, and a full mids with good clarity. Perhaps I would only ask for an improvement in the top and bottom extension — both of which I will get in the higher up Solo model.
The Graham Slee Solo SRG II
Higher up the line is the SRG II model, and this is where things become more interesting — closer to high end territory. The Novo and the Solo SRG II are very close tonally, with the Novo being the less open, entry level model, and the SRG II clearly being the better amp where the sound is much more open and spacious. Better frequency extension up and down, better sense of ambiance, clarity, and micro detail. All of these improvements in technicalities without losing one bit of the smoothness of the Graham Slee sound.
The pricing of the SRG II somewhat puts it in the same league as the Burson HA-160 amplifier (the DAC-less model), and I do think that the SRG II is a worthy competition for the Burson HA-160. The Burson has a more solid state, impactful and agressive sound, where the SRG II has a more tube-like, smoother, mellower sound. The SRG II is not a totally mellow amp, as the bass is actually fairly punchy. But the overall voicing just makes it a more relaxed amp than the Burson is. For instance, bass punch is fatter but more rounded with longer decays in the SRG II, where the Burson’s bass is faster, tighter and more articulate.
I don’t know why my brain is so used with judging a book from from its cover, because when I am listening to the Solo SRG II, it really gives me all the good things that I want from an amp, but when I take a look at the actual build of the amp in the drab silver aluminum enclosure, I somehow think that the looks surely does not match the sound quality. I mean this is an amp that is clearly ahead of the Schiit amps, the Hifiman EF-5, or the Bada PH-12 amp (review coming up soon), and it is truly something that I can live with for my personal listening device. It just seem to lack grunt in the aesthetics department.
As I have mentioned earlier, the Graham Slee doesn’t quite have that “look at me” looks, and the all around balanced and natural presentation may lack the wow factor that some other less refined amps may have, but in reality, I’ve been living with this amp for a few weeks now and I can say with full confidence that this is a really good amp. Even compared to the refined and smooth sound of the Woo Audio 6, I actually think that the Solo SRG II has a more balanced tonality and may be the amp that I choose, judging only by the sound aspect. But what can I say, the Woo Audio 6 does look much better than the Graham Slee, and sadly things like that do get into my overall judgment.
The Graham Slee Solo Ultra Linear
The top of the line model, called the Solo Ultra Linear, takes the same basics from the SRG II model and attempts to give a more linear tonal balance. Most noticeable is the presence of mid and high treble regions, which were more laid back in the SRG II. There is also an improvement in low bass regions, though the Ultra Linear is still mostly a neutral amplifier and not quite a bass champion. The added treble does boost instrument details and adds a more spacious feeling, but it’s still quite safe from being a hot-treble amplifier.
Other things like timbre and soundstage remains the same. The signature midrange that I found on the Novo and the Solo SRG II is still here with the Ultra Linear. There may have been an improvement in detail level, but I think in this case it is attributed to the increase in mid and high treble levels, rather than improvements in micro details.
Although I do enjoy the more open sound of the Ultra Linear which mostly results from the changes in treble, I really think that the Ultra Linear and the SRG II are in reality two amps with slightly different tonal balances. The SRG II has a more traditional mid-centric sound and sounds like a grown up Novo. Where the Ultra Linear presents a more linear tonal balance with more evident treble and low bass. In this case I do think that the pricing is quite fair, seeing how the SRG II costs ~$710 with the PSU1 power supply (the good power supply), where the Ultra Linear sells for ~$840 with the same PSU1 power supply. A $130 difference in price, and I do think that’s quite a fair difference for a more linear version of the amp.
The PSU1 power supply and the Green power supply.
All three Graham Slee amps require the same 24V power supply, and so you can either use the premium PSU1 or the more economic “green” switching power supply. On all the amps, you see the same improvements across the board when you upgraded to the PSU1 power supply. Instruments and soundstage are less congested, blackground becomes blacker and dynamics improve. This of course makes for a very desirable upgrade for all the different amps.
With the Novo, I may be content with using just the green power supply as the amplifier is intended to be an entry level model and upgrading to the PSU1 would put it close to the price of the SRG II with the green power supply and I’d rather go with the SRG II at roughly the same price. The SRG II is actually “high-end” enough to justify spending an additional ~$200 for the PSU1 power supply. It truly brings the SRG II from a good $500 level amp to something closer to a $1000 amplifier and if you have the budget, the power supply upgrade is well worth it. With the Ultra Linear, Graham Slee only offers the PSU1 power supply, and I do think that’s the proper power supply to use with the Ultra Linear as this model is meant to be the flagship.
Voltage and Current
Based on the same 24V power supply, I don’t seem to notice any difference in voltage swing and current capabilities. That means that the same headphone would need the same volume level on all three amplifiers to achieve the same loudness level. I’ve also tried them to drive the Hifiman HE-500 and all three models, including the Novo, did an equally good job of driving them, with the only difference between resolution between the amps.
I think these are great amps and they truly are. I especially have a soft spot for the Solo SRG II and Solo Ultra Linear, and more when they’re being powered with the PSU1 power supply. The Graham Slee Solo amps definitely becomes a solid alternative for people shopping around for a good solid state amp around $500 and up. The tonality is mellower, smoother and is more laid back than say the Burson HA-160, so depending on your music choice the Graham Slees would be a more fitting amplifier if you tend to listen to slow to medium paced music, where the Burson is better for faster paced Rock music.
The Novo carries the same Graham Slee signature as the bigger brothers, but with the Schiit Asgard being priced at $250, it’s quite a tough competition for the Novo as I can’t say that the Novo is a better amp than the Asgard for the price.
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- The Solo Ultra Linear is the top-of-the-line model and can be bought for £514.85 (~$840) supplied with PSU1 power supply;
- The Solo SRG II can be bought for £434.00 (~$710) supplied with PSU1 power supply; £314.25 (~$514) supplied with energy saving power supply.
- The Novo amplifier can be bought for £212.75 (~$348) supplied with energy saving power supply.
- The PSU1 power supply is sold independently for £141.63 (~$231).