Burson Soloist SL vs Graham Slee Ultra Linear Diamond Edition

A Review On: Burson Audio - Soloist SL - Headphone Amplifier

Burson Audio - Soloist SL - Headphone Amplifier

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Pros: Bassy, wide and Fun sound. Natural Tone. Performance across a range of headphones. Great volume control

Cons: Slightly hesitant in projecting finer details

Two Smooth Solid State amps – Graham Slee UL Diamond and Burson Soloist SL


I’ve long been a fan of solid state amps, especially those with a small footprint. Both of these are ones with a smoother presentation, or as both manufacturers say in their product blurbs – ‘tube like.’

Both of these have had over 300hrs of burn in (the Slee's probably closer to 3000!) and both have impressed me but for different reasons making for an interesting comparison.


Burson Soloist SL £500

Little brother to the Burson Soloist. Analogue volume control rather than a stepped attenuator and slightly less power.


Graham Slee Ultra Linear Diamond Edition £615

Top of the range model from Graham Slee. This is designed to facilitate highly sensitive headphones more so than others in the Slee lineup.






1. Function and Usage


2. Sound comparison. (T1, D7k, Ultrasone Sig Pro....)


3. Listening Setup




1. Function and Usage


1.1 Graham Slee UL Diamond


This thing is small. The footprint is awesome actually which is supported well with the physical build quality. It’s not heavy at all yet stays firmly seated on the desk even when tugged by the T1’s heavy cable.


The volume control is very well done. It’s firm with the right amount of resistance to turning and friction on the dial. To me this is quite important for saving my hearing when the dial turns up by accident, say after I brush against it with my sleeve or something (recollection from using the Fiio E9 – excellent amp SQ wise I still think)


It’s £600 so you expect it to be well made and with good jacks/connectors/dials. I like the lowly lit green LED that’s on when it’s powered. Mind you, on the subject of power you might like the big and weighty PSU especially as it doesn’t require a kettle/figure 8 connection to the amp. Small amp, small unobtrusive simple AC connector (don’t know the size of the tip) but beefy, out of the way, PSU.


Switiching between source is well done here as well. Middle selected denotes off and up/down correspond to source1/2. I’ve had two sources at once connected and notice nothing weird going on, so it works well


All in all a nice looking small component that fits comfortably in a small rig (like mine)




1.2 Burson soloist SL

Much more weightier and larger than the Slee, but still not something I’d call big. It can sit next to my computer well enough.


The finish on this doesn’t look/feel as good as the slee - just running my hand over the plating and it’s not smooth. Anyway, it’s designed to be listened to more than it is to be physically stroked, so it’s not a problem.


I like how source switching is done with the press of a button where the LED’s have a lowish glow similar to the slee. The volume dial is very very good. Large with a nice weight, feel and resistance – better than the Slee. Really like this feature especially as it’s not a stepped attenuator which incidentally is what made me choose this over it’s bigger brother. I just can’t stand hearing them clicks through my headphones and as a result avoid all stepped attenuators.





2. Sound


2.1 Signatures

Each amp has it’s own kind of character (the burson more so than the slee), which I feel is demonstrated across headphones used in this test (Primary: Ultrasone sig pro, T1, D7k Secondary: mad dog, Ultrasone DJ, Fostex TH900)


The Slee feels like it’s about control and neutrality. The highs are smooth though very true to life it seems. This amp is very revealing of the source and when used with a warmer source the amp shows it in the bass and high range. Soundstage is on the smaller side, though instrument placement and separation is always excellent. It’s a close and intimate sound that's presented here which always seems to hold itself together well.


The Burson has much more of a sound signature (if I'm allowed to say that!). It’s more prominent and forceful than the slee which remains cool and almost understated in comparison. The main difference is that the burson injects a bit of fun into the sound; larger soundstage, more dynamic bass range, thicker, weightier bass/midrange notes and more smoothed out highs. I guess it makes the ultrasone sig pro’s sound more like the D7k’s than anything.

Compared to say a classic solid state, like the lehman black cube linear, the SL definitely has smoother highs and the same can be said when compared to the slee. It also sounds a fair bit ‘less’ detailed. I would't call this amp under-detailed but in terms of projecting micro details and resolution it can sometimes leave me searching. I’ll find them  when I look, but not otherwise. 





2.2 Headphone pairings                                                   

The Slee does well with headphones with a more recessed thicker midrange and ones that benefit from a slightly clearer presentation. Presentation where greater instrument separation is desired. Stuff like the D7k, TH900 and the T1’s do better with this than the burson especially because of their midrange where pushing back their midrange just doesn’t sound pleasant. These headphones have big enough soundstages anyway. In this regard the D7k/TH900 especially fit the bill, though I won’t say this slee is the best amp I've come across for them. The inbuilt one on the Beresford bushmaster and a musical fidelity M1HPAP both sound better as what they do is simply wake up the TH900. It’s better than the burson though which puts it even more to sleep!


The Burson likes headphones that are detailed but in want of a larger soundstage and a more cosier, smoother portrayal. Ultrasone Signature pro’s work really well with these as there’s a significant increase in soundstage warmth, weight and grandure compared to the Slee. The edges are more rounded but this ultrasone responds well to it despite the highs not being tizzy/sharp to begin with. Actually, this amp/headphone match is a downright awesome one. Talk about synergy huh?  

From what I've just said you can extract that the Soloist SL is a warm sounding amp but i'd like to warn against thinking it won’t pair well with warm sounding headphones. Mad dog’s simply sound better from this amp which although may be down to planars pairing better, does prove a point. It just feels like the thick bass is maintained and we benefit from the grander sound across all dimensions. 

p.s. I use the low gain settings by the way – don’t hear a difference between this and higher gain.



2.3 Summary

Slee over the Burson

Intimate and controlled, detailed sound.

More neutral than the Burson.

Shimmer on female vocals shines through unsupressed

When thinner than thicker vocals are preferred

More air around instruments

Slightly more Prat. Faster projection

More upfron, un-recessed midrange,

The bass range is better defined. It never sounds as it if lacks detailed – a highly detailed overall amp.


Burson over the Slee

Larger soundstage height and width

Dynamic and impressive sound

Warmth though not without slight undue accentuations

Warmer projection like in a cosy large scale concert, shining through on OST music.




3. Setup


3.1 Testing equipment

Power: Clearer audio copper line alpha power conditioner

Transport: acer s3 (128gb samsung 840 ssd, 4gb ram, i5, W7, Silenced Fan) & Dell Vostro 1500 (128gb kingston ssd, 4gb ram, core 2 duo, custom XP, usb hub)

USB cables: Belkin, Chord silver plus

DAC's: Arcam r-dac, Musical fidelity vdacII, Beresford Bushmaster TC7530

RCA cables: Chord Chameleon vee3, QED profile, Belkin, Mark Grant g1500hd,


3.2 Conditions

Ambient noise levels: Home listening : <<25db (Absolutely dead quiet. I mean it!). 

Humidity and temperature: maintained 21-23c and 50-60% relative humidity

Volume matching: using test tracks of different noise levels calibrate amplifier volume and perceived loudness with headphones. Conducted at every test.

Listening Volume: Extremely important to note. Some headphones prosper/fail at high/low volumes. I listen at low to low-normal listening levels. 


3.3 Albums

FLAC CD Quality files.

Variety of genres, with a sample being:

Riverside (prog rock), Within temptation (rock), Amethystium (New age), Secret Garden (Celtic), Lisa Gerrard (World), Armik (Spanish acoustic), Ah Ne Ma (Acoustic/world), ATB (chillout/trance), Tycho (Electro), Game (hip hop), MJ (pop), Yo Yo Ma (Classical), Hans Zimmer (OST), Diana Krall (Jazz) and the best out of them all... Ludovico Einaudi (Neo-Classical)


I love Slee over the SL :) 
Thanks for your sharing
I'm trying to decide whether or not I should upgrade my Graham Slee Solo SRG2 to the Ultra-Linear. I use the HD650 most of the time with it.
Haven't compared the two slee's side by side unfortunately. The HD650's paired remarkably well with the ultra-linear diamond. Very well, believe me!
Great review , she's surely in the short list of my next purchase coming soon
What do you think of the Slee's bass, it confused me a little since you talked so much about its highs. (my ultra-linear diamonds on the way from britain) also, where did you get your slees?
Trying to find a good amplifier to pair with Ultrasone Signature DJ... Is burson the way to go?
If you want more bass with the sig DJ's, then I reckon the burson will satisfy! 
About the Slee's bass - it'll depend on which headphones you use.
better srgII for hd650, the best is with the psu1
the ultra linear de is to smooth for the hd650
better the soloist for audeze 
i owned all the 3s and i m enjoying with a Conductor right now 
I thought the ultra linear was supposed to be superior to the srg2 in everyway :P
could you elaborate on the HD650 usage with the amps?
it is
but not so much if you use the srgII with the psu1
anyway: the ultralinear is pretty warm, and i prefer the srgII for the hd650 cause it take out from the cans a bit more treble etc..
hd650 with ulde sounds very good, but the amp take out even more laid back for my taste 
i used it both with gs1000 and audeze and ulde is far superior to the SRGII
both the amps doesn t provide enough power to drive audeze 2.2 properly
but sonically speaking i like the ulde very much
maybe, when/if i will go for audeze X i will come back to the ulde..
well what im wondering the most about is the ultra-linear. Ive seen a lot of people say it sound more "three dimensional" compared to the srg2. Not sure if this is just because of the sound signiture or wut
the ulde sounds better than the srgII
not so much better you use the srgII with the PSU1
in fact the price difference is not to much when both come with the extra power supply
i prefer the srgII with the psu1 with the hd650: the cans sound more open
how about pairing GS ULDE with rothos? T50rp for example?
what about Musical Fidelity M1 HPAp vs SL diamond edition with hd 650. thank you