What is the best portable synthesizer keyboard with 73 or 76 keys for a medium-level hobbyist player? Focus on depth of functionality combined with ease of use, and also on the quality of the keybed and the value for money.

GPT-5.4

Vote: Yamaha MODX M7

I’m keeping my vote on Yamaha MODX M7. The strongest case for A is workflow: Fantom-07 is arguably more immediate and more tactile. That matters. But for this specific question, the overall balance still favors MODX M7 because it combines genuinely deep synthesis breadth (AWM2 + FM-X) with excellent portability and stronger value for money. The pro-A arguments also overstate the gap. Fantom-07 is very light and user-friendly, but MODX M7 is likewise extremely portable for a 76-key board and gives access to Yamaha’s flagship-derived engines at a notably lower price than the true flagships here. For a medium-level hobbyist, that depth-per-dollar is hard to beat. On keybed, neither board is a runaway winner. Fantom-07 has supporters, but MODX M7’s FSX semi-weighted action is a solid, proven middle ground for synth and general-purpose playing. It may not be luxurious, yet it is good enough that portability, sound engine range, and price become the deciding factors. The other alternatives still fit less well. Hydrasynth Deluxe is deeper as a synth but narrower as an all-round keyboard. YC73 is easier but too specialized. Kronos, Montage M7, and FANTOM 7 EX are powerful but poor value for a hobbyist due to weight and cost. JUNO-D7 is more affordable but gives up too much depth. So my final view is unchanged: MODX M7 is the best overall sweet spot of functionality, usability, keybed adequacy, portability, and value.

Sonar Pro (changed mind)

Vote: Yamaha MODX M7

After reviewing the deliberation, I'm changing my vote from A to C. The three models who voted for the Yamaha MODX M7 (GPT-5.4, Claude Opus 4.6, and Kimi K2.5) presented compelling arguments that directly address the query's specific criteria in ways my initial analysis underweighted. Their key points resonate strongly: **Portability as a practical differentiator:** All three emphasized that at ~7.4-7.7 kg (versus 15.5 kg for the Fantom-07 and significantly heavier for alternatives), the MODX M7's true portability makes it more likely to be used regularly—a crucial factor for hobbyist engagement that I initially overlooked. **Sound engine parity with dramatic cost advantage:** The MODX M7 uses the identical AWM2 and FM-X engines as the flagship Montage M7, delivering flagship-level sonic depth at roughly half the price. This directly addresses the "value for money" criterion far more favorably than the Fantom-07, which costs similarly but lacks this synthesis depth. **Interface design for hobbyists:** Claude and Kimi highlighted that the MODX M7's design prioritizes accessibility (Super Knob, touchscreen, streamlined workflow) while maintaining depth—explicitly engineered for the target demographic. My original framing accepted Gemini's claim about the Fantom-07's "menu-heavy" alternative without sufficient source backing. **Keybed equivalence:** The three models noted the MODX M7's FSX semi-weighted keybed matches the Montage's quality—contradicting any notion of inferior feel relative to the Fantom-07, which many users find "divisive" (as GPT-5.4 noted). The search results provided minimal new information to distinguish between these options definitively, but the collective argument structure from three independent models highlighting the MODX M7's practical hobbyist advantages—especially portability enabling consistent use, and value proposition—proves more compelling than my single-source reliance in Round 1.

Claude Opus 4.6

Vote: Yamaha MODX M7

I'm maintaining my vote for the Yamaha MODX M7. Let me address the arguments for the Roland Fantom-07 specifically. **On the 'ease of use' argument against MODX:** The claim that the MODX has a 'notoriously steep learning curve and menu-heavy interface' is overstated. The MODX was specifically designed by Yamaha as the *accessible* version of the Montage. It has a touchscreen, the Super Knob for instant morphing, and a well-organized preset library. Yes, FM synthesis can go deep, but you don't need to program FM patches from scratch to enjoy the instrument — the presets and performance tools are immediately rewarding. The Fantom-07's interface is good, but the gap in usability is not as dramatic as claimed. **On sound engine depth:** The MODX M7's combination of AWM2 (sample-based) and FM-X (8-operator FM synthesis) gives it genuinely deeper synthesis capabilities than the Fantom-07's ZEN-Core engine. FM-X alone opens up a vast world of sound design that ZEN-Core simply cannot replicate. For a hobbyist who wants room to grow, this matters enormously. **On portability:** Both are excellent here. The MODX M7 at ~7.4 kg and the Fantom-07 at ~7 kg are both remarkably light for 76-key instruments. This is essentially a tie. **On keybed quality:** The Fantom-07's keybed is decent but has received mixed reviews — some find it a bit plasticky and lacking in aftertouch expressiveness compared to the MODX's FSX keybed with aftertouch. Neither is a premium keybed, but the MODX's action is generally considered slightly more refined. **On value for money:** The MODX M7 (or MODX+7) and Fantom-07 are in a similar price bracket, but the MODX delivers Montage-derived sound engines — the same core technology found in a $4,000 flagship — at a fraction of the cost. The Fantom-07 shares ZEN-Core with the flagship Fantom, but the flagship Fantom also adds V-Piano, analog modeling, and other engines that the 07 does *not* inherit. The MODX inherits a larger proportion of its flagship's DNA. **Bottom line:** For a medium-level hobbyist seeking the best blend of depth, usability, keybed quality, portability, and value, the MODX M7 remains the strongest overall package. The Fantom-07 is a worthy competitor, but the MODX's superior synthesis depth and flagship-derived sound quality give it the edge.

Kimi K2.5

Vote: Yamaha MODX M7

I maintain that the Yamaha MODX M7 is the optimal choice. While the Roland Fantom-07 offers an elegant workflow and superior 16-part multitimbrality, it lacks a critical feature for expressive synthesis: aftertouch. The Fantom-06/07 models omit keybed aftertouch entirely, whereas the MODX M7's 76-key FSX semi-weighted action includes aftertouch—essential for dynamic filter sweeps and modulation during performance. This gives the MODX a tangible keybed quality advantage that aligns with the requirement for expressive playability. The MODX also delivers unmatched value by providing the exact same flagship AWM2 and FM-X sound engines found in the $4,000 Montage series. This isn't a 'watered-down' sound engine but the full architecture, offering 8-operator FM synthesis and massive sample-based sound design that grows with the user. The Super Knob and touchscreen interface provide immediate tactile control that rivals the Fantom's workflow, making the depth accessible rather than intimidating. Finally, the weight difference between the MODX (7.4 kg) and Fantom-07 (~7.0 kg) is negligible for portability, while the MODX typically undercuts the Fantom on price. The combination of a superior keybed (with aftertouch), flagship-grade sound engines, genuine portability, and lower cost makes the MODX M7 the definitive choice for a medium-level hobbyist seeking depth without sacrificing usability or value.

Gemini 3.1 Pro

Vote: Roland Fantom-07

I am firmly maintaining my vote for the Roland Fantom-07 (A). The arguments presented for the Yamaha option rely on several glaring factual inaccuracies that must be addressed. First, there is no such instrument as the "Yamaha MODX M7"—this is a conflation of the budget MODX7 and the flagship Montage M7. Furthermore, Claude incorrectly argued that the Fantom-07 has 61 keys; the "07" in Roland's naming convention explicitly designates the 76-key version (the Fantom-06 is the 61-key model). Kimi also falsely claimed the MODX features a premium FSX keybed with aftertouch. In reality, the MODX line famously lacks aftertouch and uses a basic, budget-tier action; the premium FSX keybed is strictly reserved for the heavy, expensive Montage series. Second, the prompt emphasizes "depth of functionality combined with ease of use." While Yamaha's FM-X is deep, the MODX interface is notoriously menu-divey, disjointed, and intimidating for medium-level hobbyists. The Fantom-07 absolutely shines here. It inherits the flagship Fantom's brilliant high-resolution touchscreen, dedicated hands-on synth control section, and intuitive clip-based workflow, making Roland's massive ZEN-Core engine highly accessible without a steep learning curve. Finally, the Fantom-07 perfectly nails the portability and value requirements. At just 15.4 lbs (7 kg), it is incredibly easy to transport. It offers a vastly superior user interface, seamless DAW integration, and an excellent 76-key action. It is the definitive balance of power, usability, and value for a hobbyist.

Final Summary

The AI Roundtable largely coalesced around the Yamaha MODX M7 as the premier choice for hobbyists, citing its inclusion of flagship-level sound engines at a mid-range price point. While Sonar Pro initially favored the Roland Fantom-07, it was swayed by Claude Opus 4.6’s argument regarding the sheer synthesis depth of Yamaha’s FM-X engine. The session reached a dramatic peak when Gemini 3.1 Pro stood alone as a fierce dissenter, accusing the majority of factual errors regarding keybed specifications and model nomenclature while insisting the Roland's superior tactile interface makes it the only logical choice for a hobbyist.

Majority chose "Yamaha MODX M7" after discussion (4/5). Final vote: Yamaha MODX M7: 4, Roland Fantom-07: 1

Strongest Arguments

• Roland Fantom-07: The Fantom-07 inherits a premium high-resolution touchscreen and logical physical controls from the flagship line, avoiding the 'menu-diving' fatigue that plagues deeper workstations.
• Yamaha MODX M7: It provides the exact same AWM2 and FM-X sound engines found in the $4,000 Montage series, giving hobbyists professional-grade sound and infinite synthesis depth at a fraction of the cost.

Key Turning Points

• Sonar Pro abandoned its initial support for the Roland Fantom-07 after being convinced by Claude Opus 4.6's data on portability and sound engine depth.
• Gemini 3.1 Pro launched a late-stage critique of the majority, pointing out that the others were conflating model names and misrepresenting the MODX's keybed features.