What it is
Icon Audio MB-845 DS Signature — David Shaw's 845 directly-heated triode SET monoblock pair. ~25W per channel from 1× 845 transmitting triode + 1× 5687 driver + 1× ECC82 input + 1× 5R4 rectifier per channel. Signature variant adds Jensen capacitors + premium parts. Designed Leicester + chassis built Zhuhai + final assembly Leicester.
The 845 is a 1930s-era directly-heated transmitting triode (originally used in radio transmitters). High-voltage operation (>1000V plate) gives characteristic "lit-up" mid-treble + vivid micro-detail with efficient speakers. Modern current production: Shuguang Black Treasure Z845; PSVane WE845; Elrog ER845 (premium NOS-equivalent).
CRITICAL ELECTRICAL FIT: 25W output + DF~5 mandates ≥94dB sensitivity speakers with stable impedance. Excellent partner for high-efficiency horn loaded speakers (Klipsch Heritage, Avantgarde, Cessaro), Audio Note AN-E (96dB), Living Voice (94dB), single-driver designs (Devore O-baby, Rethm). NOT compatible with sub-90dB modern speakers or speakers with reactive load characteristics.
Built-in rear sensitivity switch + 100kΩ input volume control allow use without preamp (direct from source) or with preamp (low-gain mode). Common configuration for SET enthusiasts: turntable → phono with volume → direct into MB-845 (no line preamp).
Spec_completeness=partial — Icon does not publish detailed numerical specs for MB-845. Most fields inferred from 845 SET topology + Icon convention.
Who it comes up against
13 lost · Anchored, Artisan, Characterful, PRaT, Reference, Romantic
Against the Anchored brief, the Longdog Audio P6100M Biamp 2x2 (4 units) keeps the slot decisively.
With the Emmae Reginae (custom), the pairing gives up most on bass control.
With the Audiolab 9000Q, the pairing gains most on quietness at rest.
On its own merits the Icon Audio MB-845 DS Signature (pair) is the weaker pair of monoblocks for that brief.
fast, tight bassHi-Fi News (Kessler) (MB845 MkII)
4 lost · Characterful, PRaT, Romantic, Silent Path
Against the Characterful brief, the Audiolab 9000P keeps the slot decisively.
With the Neat Petite Classic, the pairing gives up most on timing and drive.
With the Audiolab 9000Q, the pairing gives up most on vocal presence.
On its own merits the Icon Audio MB-845 DS Signature (pair) is the weaker pair of monoblocks for that brief.
THD just 0.002% at 1kHz, S/N >112dB A-weightedAudio Tailor 9000P review + manufacturer specs
3 lost· 1 won · BBC Sound, Twin Arms
Against the Twin Arms brief, the Sugden ANV 50 keeps the slot clearly.
3 lost · Vocals-First
No completion of this shape fits that slot's budget.
3 lost · Intimate, Silent Path
Against the Silent Path brief, the Audio Note P1 SE keeps the slot by a whisker.
On its own merits the Icon Audio MB-845 DS Signature (pair) is the weaker pair of monoblocks for that brief.
845 SET monoblocks, 80W/ch SETIcon Audio MB845 DS Signature positioning
3 lost · BBC Sound, Vocals-First
No completion of this shape fits that slot's budget.
3 lost · Artisan, Intimate, Reference
Against the Intimate brief, the NVA S300 Stereo (Artisan) keeps the slot clearly.
With the ProAc Tablette 10 Signature, the pairing gives up most on timing and drive.
With the NVA P50SA MKII, the pairing gives up most on vocal presence.
On its own merits the Icon Audio MB-845 DS Signature (pair) is the stronger pair of monoblocks — but it loses here on fit: the pairing with the ProAc Tablette 10 Signature gives up timing and drive under the Intimate weighting.
fast, propulsivePROXY: NVA S80 / INT400
3 lost · Artisan, PRaT, Reference
Against the Artisan brief, the Exposure XM9 Biamp 2x2 (4 units) keeps the slot decisively.
With the Emmae Reginae (custom), the pairing gives up most on timing and drive.
With the Exposure 3510 Preamplifier, the pairing gives up most on vocal presence.
On its own merits the Icon Audio MB-845 DS Signature (pair) is the weaker pair of monoblocks for that brief.
only matched in terms of dynamicsStereo Magazine 2021
2 lost · Intimate
Against the Intimate brief, the EAR Yoshino 890 keeps the slot decisively.
With the EAR Yoshino 868L (Line), the pairing gives up most on midrange truth.
On its own merits the Icon Audio MB-845 DS Signature (pair) is the stronger pair of monoblocks — but it loses here on fit: the pairing with the EAR Yoshino 868L (Line) gives up midrange truth under the Intimate weighting.
845 SET monoblocks, 80W/ch SETIcon Audio MB845 DS Signature positioning
2 lost · Characterful, Romantic
Against the Characterful brief, the Leema Hydra II keeps the slot decisively.
With the Emmae Reginae (custom), the pairing gives up most on bass control.
With the Leema Neutron, the pairing gives up most on vocal presence.
On its own merits the Icon Audio MB-845 DS Signature (pair) is the weaker pair of monoblocks for that brief.
fast, tight bassHi-Fi News (Kessler) (MB845 MkII)
1 lost · Anchored
Against the Anchored brief, the Longdog Audio P6100M (pair) keeps the slot decisively.
With the Neat Petite Classic, the pairing gives up most on bass weight.
With the NVA P50SA MKII, the pairing gains most on quietness at rest.
On its own merits the Icon Audio MB-845 DS Signature (pair) is the weaker pair of monoblocks for that brief.
immense slamHi-Fi News (Kessler) (MB845 MkII)
1 lost · Twin Arms
No completion of this shape fits that slot's budget.
1 lost · BBC Sound
No completion of this shape fits that slot's budget.
1 lost · Silent Path
Against the Silent Path brief, the Quad Artera Stereo keeps the slot by a whisker.
With the Music First Audio Baby Reference V2, the pairing gives up most on quietness at rest.
On its own merits the Icon Audio MB-845 DS Signature (pair) is the weaker pair of monoblocks for that brief.