diff --git a/internal/spe/spe.go b/internal/spe/spe.go
index b951d42..3cd7aee 100644
--- a/internal/spe/spe.go
+++ b/internal/spe/spe.go
@@ -220,9 +220,17 @@ func (c *Client) PowerOn() error {
 		time.Sleep(wakePulse)
 		return set(true)
 	}
-	if err = pulse(sp.SetRTS); err == nil {
-		err = pulse(sp.SetDTR)
+	// Each line reported separately. Not every USB-serial chip honours the modem
+	// lines, and some refuse them without saying so — on an amplifier that never
+	// wakes, "which of the two failed, or neither" is the whole diagnosis, and a
+	// single combined error cannot give it.
+	rtsErr := pulse(sp.SetRTS)
+	dtrErr := pulse(sp.SetDTR)
+	if err = rtsErr; err == nil {
+		err = dtrErr
 	}
+	applog.Printf("spe: power ON pulse on %s (model=%q transport=%s) — RTS err=%v, DTR err=%v",
+		c.cfg.ComPort, c.GetStatus().Model, c.cfg.Transport, rtsErr, dtrErr)
 	// Booting, the amp re-enumerates its USB interface, which leaves this handle
 	// pointing at a device that no longer exists — the amp came up and OpsLog
 	// still read "offline". Drop it; the poll loop reopens a fresh one as soon as
@@ -231,6 +239,26 @@ func (c *Client) PowerOn() error {
 	c.dropLocked()
 	c.mu.Unlock()
 	applog.Printf("spe: power ON — RTS then DTR pulsed on %s (err=%v)", c.cfg.ComPort, err)
+
+	// Say whether it actually woke. "The ON button does nothing" is a report with
+	// three different causes — the pulse was refused, the pulse went out and the
+	// amp ignored it, or the amp came up and the UI missed it — and only the log
+	// can separate them. Watched off the caller's goroutine so the click returns
+	// at once.
+	go func() {
+		deadline := time.Now().Add(15 * time.Second)
+		for time.Now().Before(deadline) {
+			time.Sleep(time.Second)
+			if c.GetStatus().Connected {
+				applog.Printf("spe: power ON — amp answered after %.0fs",
+					15-time.Until(deadline).Seconds())
+				return
+			}
+		}
+		applog.Printf("spe: power ON — no answer within 15s on %s. The pulse was sent; "+
+			"either this amplifier does not wake on RTS/DTR, or the adapter does not drive those lines",
+			c.cfg.ComPort)
+	}()
 	return err
 }