Positive Grid Spark 40 review

Buy a Spark 40 if you are playing at a desk or on a sofa and you want one box that covers amp models, effects, backing tracks and recording. Do not buy it to play with a drummer: two 4-inch drivers are the ceiling, and Positive Grid publishes no effects loop and no external speaker output, so there is no way to make it bigger or send it to a PA.

We have not played this amp. What follows is what Positive Grid publishes, what those figures mean in a room, and who should buy something else — which is the only kind of review this site writes. How we research sets out the method in full.

01What Positive Grid publishes

02 — The shortlist

The amp

#	Product	Best for	Price
01	Positive Grid Spark 40 33 amp models and 43 effects with Bluetooth audio and USB recording — held back by two 4-inch drivers.	A desk amp that is also an interface and a speaker	$299.00 · Check price #ad How we’re funded · price as of September 13, 2026

Rows link to the full write-up further down this page. Prices come from the live price layer only — where there is no live figure the button reads “Check price” rather than showing a remembered number.

03The 40 watts is not the number that matters

Wattage is the specification on the box and speaker area is the one that decides how loud an amp gets in a room. A 4-inch cone moves a small volume of air per excursion, and two of them are still small — no amount of amplifier power changes that, because the limit is mechanical rather than electrical.

This is why a 15 W valve combo with a 12-inch speaker is louder in practice than a 40 W amp with two 4-inch drivers, and why the comparison surprises people who shopped on the wattage figure. Speaker sensitivity varies by several decibels between models and cone area sets the low-frequency output almost entirely. Amp wattage and volume has the arithmetic.

01

Positive Grid Spark 40

A desk amp that is also an interface and a speaker

The number40 W class D into 2 x 4" drivers; 350 x 180 x 190 mm, 5.2 kg.

Positive Grid publishes 33 amp models and 43 effects covering noise gate, compressor, distortion, modulation, EQ, delay and reverb. At this size and price that is a wider palette than anything else, and it means you are not shopping for pedals in your first year.

The connectivity is what makes it more than an amp: a quarter-inch guitar input, an eighth-inch aux in, an eighth-inch headphone output, Bluetooth audio and a USB recording interface. The Bluetooth is not a gimmick here — playing along to a track through the same speaker you are playing through is the single most-used feature on an amp like this, and most rivals make you run a cable for it.

The cons start with the speakers. Two 4-inch drivers cannot move air the way a 12-inch can, and no wattage figure changes cone area — this is a desk and sofa amp, not a rehearsal-room one. There is no effects loop and no external speaker output, so it cannot be made bigger and cannot be sent anywhere but the USB port. At 5.2 kg it is also heavier than it looks.

Published specifications for the Positive Grid Spark 40

Power	40 W class D
Speakers	2 x 4" custom designed
Amp models	33
Effects	43 — noise gate, compressor, distortion, modulation/EQ, delay, reverb
Connectivity	1/4" guitar input, 1/8" aux in, 1/8" headphone, Bluetooth audio, USB recording interface
Size / weight	350 x 180 x 190 mm, 5.2 kg
What it does not do	No effects loop and no external speaker output. The 4" drivers cannot move air the way a 12" can — this is a desk and sofa amp, not a rehearsal-room one.

Specs from Positive Grid Spark 40 product page. We have not used this unit.

$299.00 · Check price

#ad How we’re funded · price as of September 13, 2026

04The two missing jacks, and what they cost you

No effects loop. If you later buy a delay or reverb pedal it has to go in front of the amp, which means it feeds the modeled preamp and gets distorted along with everything else. On clean settings that is fine. On a high-gain model it turns distinct repeats into a wash — the standard reason effects loops exist.

No external speaker output. This is the one that ends the amp's useful life rather than limiting it. There is no upgrade path: you cannot add a bigger cabinet when you outgrow the drivers, so outgrowing it means replacing it. Budget for that rather than being surprised by it.

05Where it is genuinely the best answer

1. Learning, at a desk, next to a computer. The USB interface and Bluetooth remove two separate purchases and the amp is the right size for the distance.
2. A first amp for someone who owns no pedals. 43 effects means the first year costs nothing extra.
3. Practicing along to records. Bluetooth audio through the same speaker is the feature people use most and notice least in the spec list.
4. Recording demos. A USB interface in the amp means no re-amping and no second box.
5. A second amp for a quiet room, where a valve combo is unusable at any setting you can actually turn it to.

06Who should buy something else

Anyone who plays with a drummer. That is the whole answer, and it is not close — the drivers run out long before the amplifier does. Best gigging amps covers what a stage actually requires, and the short version is headroom, an effects loop and a way out to the PA, none of which this has.

Also anyone who already owns pedals. You are paying for 43 modeled effects you will not use and giving up the effects loop that would let your pedals sit in the right place. A clean-platform amp is the better purchase — best pedal platform amps covers what that needs.

And anyone whose playing is mostly silent. If it will be headphones nine times in ten, the money is better spent on an interface and good headphones than on speakers you rarely switch on — practice amp vs audio interface works that comparison through properly.