HeadRush firmware 5.1 accepts six different NAM formats, not one, and the file you download decides how close the capture lands to the real amp. Most coverage stopped at "it runs NAM." True, and not much help.
Your Prime, Core, or Flex Prime will load A2-Full and A2-Lite, plus the four older A1 variants named Standard, Lite, Nano, and Feather. They do not sound the same. You notice it the first time you pull down a capture somebody uploaded two years ago, and the pick attack feels blunt.
Nothing is broken there. You just loaded an architecture built around a different problem, and that problem was processing power. NAM was written for computers running plugins inside a DAW, where CPU is cheap, and nobody minds if one amp model eats a core. Pedals do not work like that.
The listening data points the same way. TONE3000 ran blind MUSHRA tests with more than a thousand participants rating 37 tones against the original gear, and A2 scored nearest to the reference across the set. The rebuild also cut back the aliasing and ringing artifacts that the older architecture left on high-gain material.
Usually, you pay for accuracy in processing load. Not this time. A2-Full runs 30 to 40 percent leaner than A1-Standard, so three A2 models fit inside the budget that two old Standard models used to eat.
Steve Atkinson, who wrote NAM in the first place, has shown A2 running on HeadRush in both full and lite modes, with the lighter setting there purely to claw back headroom when a rig gets busy. That flexibility is the useful part. You are not locked into one setting for every rig you build.
On a HeadRush, they are not the cautious pick. They are a downgrade you selected for no reason. The box runs the full A2 architecture, so reaching for a stripped-back legacy model hands away accuracy to protect headroom you already have.
A1-Lite sits in a friendlier spot. It keeps most of the dynamic feel while simplifying the network underneath, and it holds up fine once a band is playing over the top of it. Still older math, though, so if an A2 version of the same amp exists, take that one instead.
A2-Lite is a different case from those old lightweights. It was engineered so that native NAM could run on embedded hardware at all, and it holds steady at 50 percent load on a 600MHz ARM chip that costs around three dollars in bulk. On a HeadRush, treat it as a fallback for crowded rigs rather than a starting point.
Retrained tone packs carry an A2 badge on the page. Older files are still there and still work, sitting behind a technical filter labeled A1 Legacy, which matters when a favorite capture came from an uploader who has since gone quiet.
One naming trap catches people out. There is no such thing as A2-Nano. The lite variant carried that name internally before launch. It was renamed to avoid confusion with the existing A1-Nano, so any forum post or video promising A2-Nano files is describing something that shipped under a different label.
All of this only matters because native NAM support on HeadRush hardware arrived without a conversion step in the middle. Formats that get transcoded into a proprietary container give something up on the way, and the reason the architecture choice belongs to you at all is that the pedal reads the original file exactly as its maker trained it.
Your Prime, Core, or Flex Prime will load A2-Full and A2-Lite, plus the four older A1 variants named Standard, Lite, Nano, and Feather. They do not sound the same. You notice it the first time you pull down a capture somebody uploaded two years ago, and the pick attack feels blunt.
Nothing is broken there. You just loaded an architecture built around a different problem, and that problem was processing power. NAM was written for computers running plugins inside a DAW, where CPU is cheap, and nobody minds if one amp model eats a core. Pedals do not work like that.
A2 captures sound closer and costs less CPU
Architecture 2 landed in June 2026 as a rebuild rather than a patch, and the accuracy gain is measurable rather than a matter of taste. Median error signal ratio across TONE3000's test set fell from 0.0062 on A1-Standard to 0.0033 on A2-Full. In plain terms, the newer format sits about twice as close to the reference recording.The listening data points the same way. TONE3000 ran blind MUSHRA tests with more than a thousand participants rating 37 tones against the original gear, and A2 scored nearest to the reference across the set. The rebuild also cut back the aliasing and ringing artifacts that the older architecture left on high-gain material.
Usually, you pay for accuracy in processing load. Not this time. A2-Full runs 30 to 40 percent leaner than A1-Standard, so three A2 models fit inside the budget that two old Standard models used to eat.
Steve Atkinson, who wrote NAM in the first place, has shown A2 running on HeadRush in both full and lite modes, with the lighter setting there purely to claw back headroom when a rig gets busy. That flexibility is the useful part. You are not locked into one setting for every rig you build.
The lightweight NAM formats exist for weaker hardware
Here is where people go wrong. A1-Nano and A1-Feather were built for cheap chips and mobile rigs, trading transient detail and low end for speed, and they look like the cautious pick when you are choosing a capture format for a pedal rather than a laptop.On a HeadRush, they are not the cautious pick. They are a downgrade you selected for no reason. The box runs the full A2 architecture, so reaching for a stripped-back legacy model hands away accuracy to protect headroom you already have.
A1-Lite sits in a friendlier spot. It keeps most of the dynamic feel while simplifying the network underneath, and it holds up fine once a band is playing over the top of it. Still older math, though, so if an A2 version of the same amp exists, take that one instead.
A2-Lite is a different case from those old lightweights. It was engineered so that native NAM could run on embedded hardware at all, and it holds steady at 50 percent load on a 600MHz ARM chip that costs around three dollars in bulk. On a HeadRush, treat it as a fallback for crowded rigs rather than a starting point.
Filtering TONE3000 by architecture saves real time
The library runs past 500,000 captures, and scrolling it blind will burn an evening. TONE3000 added an architecture filter to both the browse and the search views, so you can cut straight to A2 uploads and skip everything else.Retrained tone packs carry an A2 badge on the page. Older files are still there and still work, sitting behind a technical filter labeled A1 Legacy, which matters when a favorite capture came from an uploader who has since gone quiet.
One naming trap catches people out. There is no such thing as A2-Nano. The lite variant carried that name internally before launch. It was renamed to avoid confusion with the existing A1-Nano, so any forum post or video promising A2-Nano files is describing something that shipped under a different label.
All of this only matters because native NAM support on HeadRush hardware arrived without a conversion step in the middle. Formats that get transcoded into a proprietary container give something up on the way, and the reason the architecture choice belongs to you at all is that the pedal reads the original file exactly as its maker trained it.
